At the tender age of 11, I held a fluorescent lamp in our front garden in 1973. The tube lit up as Clive described. In this case, it was quite bright. Why did it light up? Because my Dad was a radio ham. He had rigged up an aerial that went from the front garden wall, over the roof of the house, to the back garden. I'm not interested in ham radio, but I believe this aerial is called an inverted V. He then put quite a bit of RF power into this aerial, and hey presto, the tube lit up. Some poor chap that was driving past nearly crashed into a lamp post.
At Glastonbury. In a line. with 100 other people to see how much light you can actually make... And the Guinness people there. Go for the World record of human-passively grounded fluorescent tiki lamps.
As a post office telephone apprentice I was taught two sets of knowledge in parallel. On day release at technical college I was taught electrical and electronic principles while in the workplace I was taught the PFM principle. As an intelligent individual with a pedantic nature and poor education I was fascinated with the formal electrical and electronic principles but soon realised that it’s a rabbit hole that gets deeper and more abstract the closer you look at it. In the workplace the PFM principal says this is Ohms law and this is Kershoffs law. Everything else that makes these things a fact is Pure Fucking Magic and trying to understand it will just confuse you. Over the years, I’ve realised that trying to understand the root of these things is indeed confusing to the operational level of keeping most tech going. And given that since those early years I’ve managed projects where real live quantum physics have been employed by the very clever people to deliver a working system to a customer, I’ve learned that nodding in the right place and occasional grunts keeps,things moving.
Just to be clear from the outset, I am not an electrical or electronics engineer though I studied physics for far too many years of my life. I look at electrical theory like I look at gravity. At a practical level Newtonian dynamics and gravitational theory is good enough to get you to just about any place in the cosmos you want to go to. But Einstein's general theory of relativity is a better description of what's going on with gravity - its just really fecking difficult to apply at a practical level. Like you say electrical/electron theory is a black art still not fully nailed down even though we seem to have muddled through for over 200 years. Imagine what we will achieve when we really understand it
@@RaspberryWhy The burning question that's been in my mind is, are we just extremely skilled at manipulating this concept that we have a relatively loose grasp on the mechanical function of, or are we just barely scratching the surface of what it has to offer, limited by our relatively loose grasp on the mechanical function of? I feel like I'm relatively capable of making use of electricity with the fundamental knowledge that's taught today(mind you, self educated on the subject, not by any means an EE), but I can't help but wonder if there's just a "different level" of capability here that we're just a couple breakthroughs away from.
@@RyTrapp0 As a network specialist in the states, we had a phone issue yesterday, rebooted the Charter modem, problem solved. Though it did turn out to be a regional issue.
Both theories are correct, but the magnetic fields only really come into effect on signals and high frequencies. Dave from EEVBlog made a good video on it a little back also as a response to Veritasium clickbait.
What is ingrained in my mind from a young age was when an electrician told me it was like "pushing marbles through a hose full of marbles. Add a marble in one end and one has to pop out the other end".
This is what I was taught, the electrons themselves flow slowly (we calculated it based on the equations in physics class) however its the 'propagation wave' of the analogy you give here that moves near the speed of light
@@cimmerian100 True, but the point of the theory is that the energy itself doesn't even go through the wires. The current does, but the energy for the work done comes from the EM field.
Very simplistic. There would be a large propagation delay as the wave of electrons hopping between atoms at a tenth of a millimetre per second would take hours to reach the other end and pop out! All the electrons move at once because the field propels them all at the speed of c. Engineers struggle with this concept because few of them are physicists and therefore have to unlearn a lot of simple stuff that enabled them to do their jobs, but is still an incomplete description of how the world really works. The Universe has no obligation to make sense!
A practical example is to recruit a friend who is both a smoker and tuba player. With a lungful of cancer-stuff have him play his favorite ditty. Wait until you can see smoke coming out of the bell--it will be a considerable time after you hear the sound.
Veritasium clearly wanted to explain the physics of electromagnetism, in particular the Poynting vector and the concept of the electromagnetic field (which is a different thing to "electromagnetic fields" by the way), and in so doing tried to come up with a simple thought experiment that would show how counterintuitive the theory is for the average person. To make it work, he assumes the wires are superconducting, that the switch and battery are ideal and that the lamp will come on with any current above zero, even infinitesimally small. He also assumes the usual things about the experiment being completely isolated from interference from the rest of the world. The problem is that he leaves the viewer with the impression that energy flows from the battery to the lamp *primarily* through the 1m gap, rather than "along" the wires. To justify this he does a bait and switch. He shows a small electrical circuit with a lamp and a switch in which the Poynting vector is somewhat correctly drawn traveling more or less across from the battery to the lamp (in fact a vector has a magnitude and direction, it is not a continuous curve from one location to another). He then switches back to his lightsecond setup and implies that the Poynting vector points directly across from his battery to the lamp in that setup too and so implies that most of the energy is transmitted from the battery directly across to the lamp at the speed of light. There are many problems here. Firstly, in his setup, the potential difference initially exists across the switch, assuming his lightsecond long cables took more than a couple of seconds for him to set up. This means that the disturbance which causes current to flow, and resulting electromagnetic fields, propagates from the switch, not the battery. Second, in his setup, the Poynting vector is zero at the surface of the wires because they are superconductors (in electrostatics, for wires with nonzero resistance the Poynting vector usually points into the wires in DC conditions due to ohmic heating, i.e. the energy is flowing *into* the wires to heat them; but that is not the case in Derek's superconducting setup). But external to superconducting wires the Poynting vector is *along* the wires, parallel to them, but with rapidly decreasing magnitude as you move further from the wires. In other words *MOST* of the energy flux is along and very close to the wires, in the electromagnetic field, which much more easily aligns with intuition than Derek's extremely misleading video. Thirdly, Derek very strongly hinted that his claim could be experimentally verified, which is bollucks. Even if he just uses lines of a kilometer instead of a light second, he won't find a lamp that will turn on with infinitesimal current. He won't find a kilometer of cheap superconducting wire either. The reality is the globe will light after about 1s as the bulk of the energy is concentrated very close to the wires. However, having said all that, there is a transient that propagates from the switch along the wires that induces a tiny (negligible) current in the wire 1m away due to coupling through the electromagnetic field. If the light could turn on with infinitesimal current it would light after just a few nanoseconds. In this specific time there is a very small amount of energy *radiated* from one side to the lamp on the other side at the speed of light. It's not steady state and will fluctuate due to capacitive and inductive effects and signal bouncing around and so on. But technically it is there. It just has nothing whatsoever to do with how the potential energy in the vicinity of superconducting wires is distributed in the large. The fundamental point that individual electrons do not have to move all the way around the circuit to the lamp for it to light is however correct. The *average* speed of the electrons is in fact very slow, orders of magnitude slower than propagation of energy in the electromagnetic field. The energy is in fact transmitted through the electromagnetic field in the direction of the Poynting vector, but for all intents and purposes this happens to be parallel to the wires mostly just outside the wires in the steady state. The whole thing is complicated by the fact that as phrased, the problem is an electrodynamics problem and not an electrostatics problem. Thus many of the usual equations people want to apply simply aren't valid until the system reaches steady state. It's also complicated by causality. For example you can't think of the wires as a giant capacitor because in 3ns only 1m of the wire either side of the switch is even relevant to consider due to causality (finite speed of light). By the way, there are some fascinating experiments that have been done to measure the electromagnetic field just outside an ordinary resistive wire using tiny seeds. In the vicinity of the wires the Poynting vector really doesn't point away from the battery towards the lamp when a DC current flows, but mostly along and slightly towards the wires. However, at the lamp, due to the fact that it is a resistive element, the Poynting vector points mostly towards the lamp. Energy comes out of the region surrounding the lamp because a potential is established there due to the wires carrying it there. This potential establishes a current (flow of electrons) in the lamp, and the potential energy in the vicinity of the lamp due to the potential established by the wires is converted to light and heat in the lamp. In the DC case *zero* energy is radiated from the battery, and I really mean zero, not approximately zero. Instead, the Poynting vector at the lamp shows the energy flux from potential energy in the region about the lamp into the lamp where it is converted to light and heat energy. I've tried pointing this out to the nerds who claim otherwise but years on they still insist they are right.
Even with all these magic tricks, his answer is still wrong, because just closing the switch does not cause instantaneous step-like change in EM field that can be picked right after 1/c seconds. This is not what happens when you close the switch. EM fields can only change when sufficient amount of electrons had time to change their positions and average velocity.
@goodwillhart I agree with just about everything you say, but I have one small quibble: you state: "But external to superconducting wires the Poynting vector is along the wires, parallel to them, but with rapidly decreasing magnitude as you move further from the wires." That's pretty much untrue. The Poynting vector has a magnitude and a direction, but has nothing to do with the orientation of the wires. If you have a battery, two wires and a bulb like in Clive's diagram, it doesn't matter if the top wire goes up, then right, then down to the bulb. The electric field will have a direction from the top wire to the bottom wire, while the magnetic field will be around the wire. If you consider a cylinder surrounding any part of the wire, then calculate the Poynting vector for the flux into one end of the cylinder, it will be equal to the Poynting vector for the flux coming out of the other end of the cylinder, and it will always point from left to right, i.e. from battery to bulb, regardless of which way the wire is pointing. If you change the orientation of any part of the wire, you change the direction of the electric field between it and the other wire in such a way that the Poynting vector will remain in the same left-to-right direction. It has to because the Poynting vector is just a way of calculating flow of electrical energy, and electrical energy is either conserved or transformed into an equivalent amount of another form of energy (such as in the bulb).
@@tbird-z1r ...and thus, the Veritasium video is more like confusing psycho-babble than anything enlightening, whatever level at which viewers appreciate electrical theories. He should take the video down and re-make it with more scientific rigour - this is the first time he's really disappointed me.
Veritasium clearly wanted to generate controversy and clicks, and thus revenue. Mission accomplished. His goal was not to increase understanding, because he did exactly the opposite.
In the original Transatlantic cable, they didn't use sounders but instead used very sensitive galvanometers. It took on the order of ten seconds to transition from a dot to a space. The throughput rate was very slow. As the cable began to fail, they kept stepping up the voltage until the cable completely failed. They had to wait until after the American Civil war to run a new cable. Two ships carried the entire assembled length of cable (tested in harbor before the ships ever left) They then sailed to the half way point and began laying the cable in opposite directions until they reached both shores.
That slow change was probably a capacitive effect, the very long run of two conductors separated by a dielectric material acted like one ginormous capacitor. So when they closed the circuit, power would flow in but had to slowly charge that huge capacitor before any noticeable voltage increase would be seen at the other end.
What's the American Civil War got to do with it? The cables ran England - Ireland - Newfoundland and were designed, built and layed by British companies. As more cables were layed, increasing amounts of American investment money were needed. Is that what you're suggesting? The second cable was delayed because of a lack of US investment, caused by the war? That's not in my history books. Or is this another 'America built, discovered and invented everything' sort of theme?
Early telegraph systems used a single open wire and earth return over significant distances and worked just fine. The problem occurred when these wires were laid underground or under the ocean. The additional capacitance of the cable, coupled with its resistance, caused the rise and fall times of the current to be unacceptably long. When the first transatlantic telegraph cable showed this effect the reaction of the chief engineer was to increase the applied voltage. Unfortunately the increased voltage was too much for the insulation which broke down, and it didn't even cure the problem. It was the invention of "loading", which deliberately increased the inductance of the cable which, somewhat counter-intuitively, solved the problem. I can't remember off the top of my head which scientist it was that came up with that, but it was employed on later transatlantic telegraph cables. The technique was also used on telephone circuits until quite recently. When digital transmission (PCM) replaced audio on some medium-distance circuits in the 1960s and 70s the loading coils were replaced by digital regenerators.
@@DUKE_of_RAMBLE Sadly not. I stole the name for my YT presence as my real surname name is unusual making it too easy for someone to identify me. But I am a retired telecomms engineer with a strong interest in the history of the industry.
As far as I know the output end of the early long-distance cables was not a sounder but an optical galvanometer. This is a typical electrical meter with a coil in a magnetic field, but the coil is very delicately balanced and has a fragment of mirror mounted on it. A light beam reflects off the mirror and illuminates a scale. The light beam takes the place of the needle in a regular meter. The advantage is that as the light beam has no mass it can be made arbitrarily long to amplify any movement in the mirror.
That was put on after the cable did not work because the signal was too weak. It saved the day and all the money invested and they use the cable to send messages.
@@SynKronos perhaps, but the significance is that there isn't the momentum which would impact the amplified signal. Consider a hypothetical device which was moving a long metal arm. Short movements at the pivot would be amplified into observable large movements, but changing direction of the arm would not be instantaneous and would have to counter the momentum in that arm. There's still a moment in moving the mirror at the pivot, but the arm is now replaced with a beam of light. That beam doesn't have a moment, so the change in direction is only affected by the moment of the mirror, so the amplification can just be extended by extending the range that the beam is cast.
Originally, it was not a mirror galvanometer. They had to bring in Lord Kelvin who added the mirror galvanometers as a way to solve the many problems that BigClive so nicely described. Veritasium's analysis treats batteries like the sun. The sun clearly sends energy, this power, to the earth through the vacuum of space. Batteries do not work that way, or else you could just show the battery to a light bulb and it would light up. "In theory, practice and theory are the same. In practice, they're not." - Yogi Berra
@@SynKronos If you are referring to the light beam, it has momentum rather than mass, doesn't it? If you could somehow isolate and "weigh" a photon, I seem to recall it would be massless, though is does have energy that could be measured as mass due to the mass-energy equivalence. There would (theoretically) be some microscopic displacement of the mirror due to the impact and reflection of the incident beam, but (at a guess) it would be insignificant, even in this experiment. (Note that my uni physics was near 40 years ago, so some of this physics is a bit dusty up there in the ol' attic. Feel free to refresh it!)
At 5:45 "The formulas being applied to justify saying the current flows on the outside; I get the feeling that they largely apply to the radio part of the spectrum". No Clive. The claim is that the _energy_ is flowing outside of the wire. Nobody is saying that the current in the circuit you drew is flowing anywhere except inside the wire. But the wire connecting the battery positive to the bulb (call it the red wire) will be at battery voltage (say +1.5V) and the wire connecting the bulb to the battery negative (call it the black wire) will be at 0V. That means a voltage exists between all of the red wire and all of the black wire that gives rise to a static electric field that we call E between the wires which is the change in volts per metre from the red wire to the black wire. There is also a static magnetic field going around the wire which is associated with the steady current flowing through the wire. Someone called Poynting realised that when we have an electric field (in your diagram from the top wire to the bottom wire) that crosses perpendicular to a magnetic field (in your diagram going into or out of the paper) then you could calculate what is called the vector product ( *E x H* ) and it would be a vector with a magnitude equal to the energy flow and a direction perpendicular to both E and H (in your diagram, from left to right, i.e. battery to bulb). In other words, there is a way of looking at the static electric and magnetic fields that occur in a DC circuit like your diagram and deriving the power delivered from the battery to the bulb. It comes out to be exactly equal in size to the conventional volts times amps that we normally use. In that sense, we can say that the electrical energy flows via the static electric and magnetic fields that exist outside of wires that have current flowing through them, and calculate *E x H* . But we could also say that the energy flows with the current and calculate V times I. It's just two ways of looking at the same thing, and the result is necessarily the same. You'll note, therefore, that I've emphasised the static nature of the fields and the steady current. There's no electromagnetic radiation of any frequency involved, nor any waves, and certainly not "the radio part of the spectrum". That's for your circuit drawn around the 5 minute mark, and I though you might appreciate a clarification of what is actually going on in that simple circuit. Nevertheless, as soon as you get switches closing and both voltages and currents changing, you're in another ballgame. In that case, there are transient electromagnetic waves radiating through the air which can also carry energy (although not much in comparison to the energy associated with the current flow in the steady case). It was the ability of the original presenter to conflate these two different phenomena that has led to all the debate.
Sanity check: Run your wires through a faraday cage with a 3mm cable penetration. Heck, make it an S-bend. Does the bulb illuminate? Well maybe the situation here is more complicated than we had hoped. Edit: For a bonus put a smaller mumetal cage around the bulb to make sure the H field is also completely dealt with.... still illuminating? Damn.... electricity doesn't care about our Poynting Vector derivations.
And the Pointing vector derivation doesn't care about your electricity. The faraday cage doesn't "turn off" fields, it simply confines the field (that we care about) to the 3mm cable penetration. For DC this difference is immeasurably small, as they are mostly there already, but for signals in the radio frequency spectrum the difference may be significant. Fields are always conserved. Think about a simple electron in empty space, and the electric flux it creates which is always proportional to its charge, no matter at what distance you measure it (over the whole sphere!). Now place a metal sphere next to the electron. Locally the field is changed, but as the metal is neutrally charged, the overall charge is not changed and the flux is the same. Now put the sphere around the electron. Does the field go away? No! Metals are just (in this case neutralized) masses of movable electrons. They will be repelled from our original electron, so the inner surface gets positively charged and the outside negatively, creating a dipole field with the exact same global flux outward as the initial electron had. Analogous rules apply for currents and magnetic fields. Fields are ALWAYS conserved. If you do the pointing derivation for energy transfer, it matches perfectly with the real world. In DC circumstances the energy is confined to the conductors. In high frequency situations the whole circuit becomes (to simplify) an amalgamation of capacitors, most of the energy follows the path of least impedance, some will go straight through the air. It is counterintuitive. Like relativity. Doesn't change the fact that it's reality. And yes, Veritasium's image is misleading as it shows lots of the energy fields going outside the circuit in a DC condition, which is wrong.
He has a tendency to do that, he did a video on self driving cars a while back, titled something like 'why you should want driverless cars now' and how they have the experience of millions of drivers and conveniently left out the fact that all that experience was of the same 5 mile stretch of road. The thing hilariously does an emergency break when someone walks past on the pavement, if it wasn't a controlled car park it would have been a dangerous manoeuvre and he tries to play it off as if it was a good thing, and all I could think was how bad were all the other takes if you were filming all day and you left in the shot that nearly gave you whiplash and how much did they pay you for the sponsorship?
Infotainment needs to be taken with a pinch of salt. Popular RUclipsrs always prioritize making a video over making it worth anything. Of course, everyone loves to feel like they are educated after just watching a video, so sycophancy kicks in. If one really cared about learning physics, there are plenty of lectures from reputable experts out there, but there are fewer bright colors and jumps cuts.
@@YearRoundHibernater What's worrying to me is that, him having spoken about this publicly before, he's starting to stray past his original goal with the channel which was to "Create educational videos that would blow PBS out of the water" rather than clickbait and semi-researched videos. I know a semi-popular youtube creator and I've seen the huge struggles behind the scenes where even with good intentions you can create clickbait and the only things you can react to are the hate comments that seemingly come no matter what you make. It makes it very, very challenging to get good criticism on things unless you have a specific group of viewers who can give you feedback (Patreon discords can be a great example of this) or have a third party review videos before they can come out (which has a whole host of other terrible problems). I had to stop watching veritasium once it started getting into stuff I've personally experienced or know someone who is an expert in those fields and it turned me off of the entire channel. I know his intnetions are genuinely awesome, and the hard work he's done to make it happen SHOULD be praised, but the last 5 videos have just felt extremely underwhelming and very one-sided compared to videos in the past. People have given much better criticism than I ever could on this in the comments of each of those videos but I don't really know if there's a good way to communicate that.
The best thing about the veritasium video is seeing all of these videos discussing the subject. I certainly have learned more from all the discussions happening in videos.
After watching the many videos about Vertasium's video. First of all my head is exploding. Second I think he was on about the speed of electron flow as the electrons only move slowly through the conductors as opposed to the fact the light in the bulb is quite instantaneous. In another video, they described the flow as different in the centre than towards the edge of the conductor. My brain is still exploding.
@@atlanticx100 It really shouldn't be exploding. He is very misleading cause his version of the light bulb "turning on" is just induction in the wires causing the light bulb to turn on for a brief amount of time, and since its DC electricity this induction goes away as fast as it was first generated.
@@atlanticx100 Think of it the same way as pushing a stick. The other end of the stick responds pretty quickly, at the speed of sound, in the order of 1000m/s depending on what material the stick is made of, while the actual atoms in the stick would be moving at maybe 2mm/s.
@@bigclivedotcom What bothers me most about the Veritasium's video is that it's almost a copy of a The Science Asylum's video from 2019, I have no idea how original that is by te way; ruclips.net/video/C7tQJ42nGno/видео.html
Basically, Veritasium’s explanation is just a difference in semantics. He drew the fields outside the wire and said the power is in the fields, not the wire. But those fields are created by electrons moving in the wire, and so the wire is still necessary! It’s possible to transmit power wirelessly, but it’s inefficient at a distance. We do it all the time with radio.
What he said was that the energy was transfeared by the electromagnetic fields around the wires not by the electrons in the wire. What I didn't think about watching veritasums video is the connection to photons! Accelerating electrons will produce photons not electrons with constant motion.... Don't know where I am going with it. Can an electromagnetic field propagate energy without photons?
@@lubricustheslippery5028 a photon is the smallest discrete measurement of an electromagnetic field. You can get it to behave like a particle (double slit experiment) but it is in fact the electromagnetic radiation. So to answer your question, no, by definition! If you have EM radiation, we call it’s smallest possible state a photon.
His assertion about the super long cables with switch and light next to each other is completely wrong, though. I'm speaking from a practical point of view - a smaller scale version of that experiment is performed all the time to measure the electrical length of RF cable used in phased array RADARs. For a given type of cable, the physical location of the ends of the cables does not make any difference to the propagation delay, only the length of the cable.
I'm curious about why - if the power is in the fields and not the wire - does the wire get hotter as more current passes along it? That seems to indicate there's something power-related going on in the wire itself. And for that matter, what's happening at the lamp itself where all this power is being used? If it's an incandescant lamp - which is just another sort of wire - is all the power suddenly switching from being "in the fields" to being "in the wire" in order to make it glow?
I have used a Time Domain Refectometer for years and the thought that cable length and its distributed impendences are not important to electrical flow in a conductor, is, well idiotic and an insult to Charles-Augustin de Coulomb.
Luckily Derek's mental exercise contains all manner of practically implausible assumptions, so it would be a little foreign to expect a practically plausible result.
Without 'repeaters' every so often to reform any pulse wave shape, the inductance and capacitance of the cable will 'reshape' the square wave of a morse code signal into something similar to a sine wave. The overall metal jacket will look like a shorted turn to the signal further degrade the signal. I shook my head when I read 'Vs' description but there were already too many comments. Thank you for challenging his missive.
Not repeaters. Heaviside should have made millions when he invented his Telegrapher's Equation. Hang just the right inductors and or capacitors all along your DC telegraph cable, and dispersion is set to zero. This also removed the barrier from phone lines (which were distorted and useless if longer than about 50 miles.) But Bell Tel screwed Heaviside out of his invention of long-distance telephone, instead promoting their own golden boy, M.I. Pupin, who simply lifted Heaviside's invention; taking false acclaim as if he'd invented it.
The capacitance of microphone cable on the cheap stuff can be heard by picking up the cable in the middle and dropping it on the floor. An audible sound can be heard.
4:45 What I've once read, was that Maxwell began doing calculations on some phenomenon, and then his calculations showed that that phenomenon actually propagated at a *very* particular speed, c, the same speed as light. So he concluded that the phenomenon, electrical fields or magnetic fields or something, was somehow a kind of light, or was similar to light. It's almost three decades since I read that in a popular science book, though, and I've never really been able to understand advanced physics because calculus is a mystery to me.
Maxwell did unit analisys of the permeability of a vacuum (4*PI*10^-7*Hm^-1 = (kg * m^1 * s^-2 * A^-2) ) multiplied by the permittivity constant (8.854*10^-12*Fm^-1 = (A^2 * s^4 *kg^-1 * m^-3) ). So the kg, and A components cancel out, and you are left with (m^-2 * s^2) . He noticed that the units left remaining gave a speed, and when he calculated that speed he noticed that it was very close to the estimate for the speed of light! i.e. c = SQRT(1/(4Pi*10^-7 * 8.854*10^-12) ) = 299795637.7 ms^-1
My problem too, Peter. Despite the intervention of many, anything but the simplest maths was a complete blind spot for me. I would have loved to be an electrical engineer - well, any sort of engineer, really. I had to content myself with studying a biomedical degree.
@@johndoggett808 I doubt he reached his result by doing unit analysis on the famous equations that was his result and on the SI system derived from his results.
@@johndododoe1411 He was doing unit analysis on two constants, not on equations. Obviously he wasn't using SI units, but a length is a length, and a second is a second. It was when the speed of light popped out, that he realised the connection between light and electromagnetism.
A curious tidbit about the 'arrow' on diodes and transistors. It's representative of a point contact diode. The line across the end of the arrow represents the germanium crystal and the arrow represents the cat's whisker. It doesn't have anything to do with current flow. It's just a happy coincidence it matches conventional current. The same symbol was used for point contact transistors. The base is a germanium crystal and the two diagonal lines coming off it are the collector and emitter, where the emitter was the one with the arrow head. That's a PNP transistor, as all point contact transistors are, and the arrow was simply flipped for NPN transistors.
Something I was told by a dead Imperial College physicist: "Optical is really a tiny part of the spectrum. It just happens to coincide with the tight band of radiation that matter (solid stuff) reflects". The fact we can see "light" is no accident.
"Optical" is actually a very narrow part of the EM spectrum that coincides with the the peak frequencies emitted by the sun that reach the Earth. It's hardly surprising that animals evolved with eyes that can respond to (i.e. see) what is the strongest EM stimulation commonly available to them. Matter, solid or otherwise, reflects a vast range of different frequencies of EM radiation, as radio hams are very aware.
I’ve been teaching atomic structure for longer than I’d like to admit. I liken our understanding of it to casting shadows. In the case of the electron, we can determine the mass of a single one very precisely, but we can’t know it’s exact location. We can count the number of electrons that move when a current is passed, but, as you point out, we have no way of knowing how that current actually moves through a conductor. It’s important to approach new theories with an open mind, but also to apply the logic we’ve learned to them. Keeping a civil and informed discussion going is worthwhile.
Dave at EEVblog actually explained this one for me (odd cause I usually fall asleep before he gets to his point). I twigged that Veritasium he was talking about signals while ostensibly suggesting it was about power when he brought up transatlantic cables, but his answer violating the speed of light (and the unit/dimension problem) made no sense to me till Dave pointed out that he has his loop was 1m from side to side and that was part of the thought experiment and not just a constraint of trying to get a prop in frame. The original video was talking about free space signal propagation, and not about power delivery (the zero resistance wire is a red herring, but the infinitely fast turning on bulb with any potential at all was very well glossed over). Frankly I would watch a video about radio any day of the week, selling it as being about power delivery is just fraudulent.
From what I understand the most misleading part of the VT setup is that the "immediate wireless effect" of the battery on the light bulb will probably be the same even if they are on different circuits not connected to each other at all. So what's the point of presenting it like that?
Even with the magical lamps that is "turned on" by any voltage¤t(why it isn't always on then?), zero-resistance wire(but it still has electrons carrying charges and they continue to behave like electrons, and it has capacitance and inductivity?), with infinitely small and infinitely fast and otherwise perfect switch, Veritasium's "1/c" answer is still wrong. Because at the moment of closing the switch no instanteneous change in EM field is created, that can be received at 1 meter after 1/c seconds. This is not how switches work, this is not how antennas work. You need non-zero time for charge to re-distribute by traveling along the wire around the switch and *only then* there is a change in electric potential and current that will cause a change in EM field that can be picked up by the opposite side over the air gap.
Dave made a very bad simulation, actually. I recommend watching videos from "Z Y" channel, he presents some proper simulations and comes to the same conclusion as the experts Ve has consulted.
I've worked in the telecommunications industry and have seen some amazing faults related to several aspects you have mentioned. Most commonly on analogue lines galvanic damage due to rain water. But I've also seen a sympathetic signal resonance between a taxi cab radio dispatch and a telephone line to a bookmakers. That was fun.
What made Veritasium's Video so frustrating is the lack of an explanation of his assumptions - and the implications of these. For example, his "light bulb" is a device which cannot exist - it is able to turn on for any infinitesimally small current, yet it does not get turned on by the leakage current of the air.
I think VT's biggest problem is not making the distinction between "a signal" and "a flow". A signal is seen at the light bulb almost instantly because of induction between the wires, and that signal itself induces a flow, in reverse to the flow that would eventually come when the actual electrical flow picks up. Better, when the flow _does_ catch up, a lot of it will have been interfered with by the reverse flow transmitting wirelessly as a signal between the wires through induction. The undersea cables are related because, as Clive was getting to, nature is _full_ of tiny magnetic and electrical fields and potentials, so trying to pass a stable one through all that will see signal interference from millions of chaotic sources, which don't do much individually but add up over hundreds or thousands of miles.
He treated "flow" and "field" as mutually exclusive, when "field" is actually the mathematical description of the forces exerted by particles (E-field) and their flow (B-field). It's like saying that mass is released as energy, BECAUSE of the equals sign in Einstein's famous equation, or that time flows one way BECAUSE of entropy. A description of something is not a force, it has no cause or effect.
I'm not knowledgeable on this stuff, but don't you need AC for induction to happen? I thought that for that reason transformers only apply to AC. My understanding is that a DC current will cause an electromagnetic field, but it's not a _changing_ field so it won't induce a current in the other wire.
@@captainchaos3667.. ok , it's been a long time , so I hope I get this right .. keeping it simple .. think DC solenoid / relay etc .. the DC current "induces" a magnetic field , and makes stuff do stuff ... solenoid is probably easiest to imagine
@@captainchaos3667 you need changing magnetic field to induce current. If everything is stationary then you need AC for that. But you can wrap some wire under DC around a core, and move that core around. That's actually how generators work.
I don't quite understand what you mean by "signal is seen at the light bulb almost instantly because of induction between the wires". Signal is seen, induction definitely happens, but why is that an explanation?
Last weekend I vaccumed my room and got shocked when I touched the metal tube. The arc was about 1.5cm long and hurt like hell. Can confirm they are "special".
@@mathewcherrystone9479 I've bought two cotton tracksuits and let me tell you they love the fluffy polyester blanket on my couch. I've never been that charged in my life, not only does every door handle bite me like it's defending its young, but I also have fried a set of fairy lights by touching it and yes the arcs I create are quite impressive 😂
So thankful you addressed this. In a way you describe his thought better than he did (for my brain). I love when 'in theory' goes against 'in practice'.
@@matsv201 I don't think that click bait and the content (in that case the quality of Veritasium's explanation) have to be related. If they were, it wouldn't be click bait. In that case, I think Veritasium actually tried to make a clear explanation about how energy is transported, but simply did a job so bad, it caused confusion instead.
My first reaction to veritasium's video was "if its the fields carrying the power, why do you need the cable?" His whole explanation with the chain and mentioning how our electrical system has breaks in it really rubbed me the wrong way. the electron drift in one wire induces the drift in an adjacent wire either through inductance or capacitance. In between these breaks, energy is transferred from one side to the other via electric and magnetic fields. But inside the wire it really is that electron drift carrying the energy. The whole reason an incandescent lightbulb glows to begin with is because the electrons drifting through the filament have a sort of electromagnetic "friction" with the stationary nuclei that produces heat, which in turn produces black body radiation. Placing a lightbulb in a strong electromagnetic field without allowing the electrons to drift would not illuminate the bulb.
@@Dukey8668 Can you fundamentally make a difference between whether the energy is contained in the field or the wire? If one does not just exist without the other. They're potentially just two ways of looking at the same thing. Like of course charge spans a field that causes a measurable physical interaction at a distance, but whether the field "contains" that energy seems like an entirely pointless squabble.
@@SianaGearz " Can you fundamentally make a difference between whether the energy is contained in the field or the wire?" Is the energy in a garden hose in the water or the hose? Without the hose the water just falls to the ground, the hose merely contains the energy that the water has. This is probably a fairly apt analogy for EM fields and wire.
@@Dukey8668 so what? The field does describe the interaction that happens at a distance, this is the whole purpose of this construct. It doesn't say anything about where the energy is "contained". In fact we don't know how the nature works, physics as a whole is a predictive model based on conventions and constructs that appear useful, they don't have an ambition of being true in the fundamental sense. These constructs are functionally true because their predictive power is proven experimentally, they are not fundamentally true, in fact fundamental nature of most phenomena is likely unknowable. And science popularisers like Derek I feel are doing the world a disservice by presenting these models as the fundamental or absolute truth.
Part of the reason buried cables power cables aren't as affected by capacitance to the earth is that the phases are balanced. If you observe a section of cable from the outside the total charge inside is always the same.
5:20 Nitpickers’ corner: between Microwave and IR, there’s a range of frequencies up in the low-mid terahertz range that we hadn’t really figured out what to do with for the longest time. The last I’d read about it (about 8 years ago I’d say), the prevailing research was on using it for backscatter scanning, in airport security and possibly medical imaging applications. Hoping someone will chime in with any current knowledge on this.
The problem is none of our modern methods of making electronic components will work above about 1 Terahertz. So electronic circuits don't work there. Below long IR, optical technologies really don't work. So there's a small no-mans-land in between radio and optical that our technology currently can't exploit. If we could make electronic components like diodes that would work at optical frequencies, we could make nearly 100% efficient solar panels with bazillions of optical diodes and wavelength sized dipole antennas. But we can't, so we're stuck with the photoelectric effect that only allows about 30% efficiency.
@@adamrak7560 What does plasmon resonance have to do with practical electronic circuits? Can you use it to make a radio that operates above one terahertz?
@@stargazer7644 Well that field is actually called plasmonics, and yes it can dovetail with modern electronics. Given your name I assume you know submillimeter observatories also exist under the umbrella of radio astronomy. Historically people have had to use special vacuum tubes like travelling wave tubes and klystrons to amplify such signals but apparently there are actually transistors (HEMT's) that can now provide gain in that regime. Needless to say it's a field of active research. en.wikipedia.org/wiki/High-electron-mobility_transistor
@@whatelseison8970 Wow!!!! That’s really cool, that article also explains how GaN-based power transistors are so efficient compared to their silicon equivalents, something I hadn’t really read about before outside of speculative press releases.
I think it's pretty amazing people invented all these different types of components when our understanding of how energy moves isn't so clear and potentially was wrong. Like when the diode was invented the inventor was using a model where electrons were moving from positive to negative.
Apparently not, from a comment above, the first diodes were vacuum tubes, where knowledge of electron flow was just fine (and pretty much required I would think). The electrons spread out as they head towards the positive plate.
This is why I've always felt that you do not have to be a complete expert to fix/build/make something...especially with access to the internet. So many of the major inventions we use every day, were not understood when they were invented! Even youtube was meant to be a dating website...here we are talking electrical theory!
The symbol for a diode comes from the old vacuum tube, where the electrons of the filament are being emitted towards the plate. The triangle is the cloud of electrons spreading out from the filament towards the plate.
@@crackedemerald4930 I wondered how the Veritasium theory fitted with valves, CRTs etc. These (esp CRTs) operate with high velocity beams of electrons flowing in a vacuum, or at least that's what I was taught.
@@davidfaraday7963 it's strange how People are calling it *his* theory. But i guess it's easier than "pointing vector theory as presented by veritasium"
Nick over at The Science Asylum did a video on this about 3 years ago, without all of the distractions that Veritasium added: ruclips.net/video/C7tQJ42nGno/видео.html . His video includes a nice time-line, beginning with Ben Franklin losing the coin-flip about which charge actually carries current in wires, jumps ahead to Joseph John Tomson's discovery (1897) of the electron (in cathode ray tubes) and back to John Henry Poynting's theory of energy flow (1884, so not exactly "new", and not dependent on electron theory at all, since the electron hadn't even been "discovered" yet). While this theory is counter-intuitive overkill for understanding (low frequency) power flow through wires, if it wasn't true in all cases, there would be no such thing as radio.
Yeah, I keep trying to get people to go look at that one. The implications are far, far more important than any of the examples Derek used. This one quote: "According to Poynting, energy _cannot_ flow in the same direction as the charge." It's a vastly more powerful claim, and proven, as you said.
@@oasntet But is that because Electrons are negatively charged ? ( and have low denstity/mass). What happened to the Positron - is that Antimatter related ?
@@highpath4776 I'm not 100% certain on the antimatter version of it, but I'm pretty sure it is identical except that positive charges would be flowing from the positive end of the battery; the Poynting vector would therefore still be the same. But yeah, it's because a moving charge generates a magnetic field, and the two together create a change in the omnipresent EM field, and energy flows due to that change.
EEVBlog's video on it was quite good. Main bits I recall is that the light will turn on at C/1m time, but that near-instant effect will be from capacitive effects and be very dim for some amount of time. He also seemed to say the answer would be different with AC lines, but don't think he went into why that is. So from his viewpoint, the bits about high voltage lines are unrelated to the original question posed Very interesting points you bring up, and very much seems like Veritasium didn't limit the theories he talked about nearly as well as one should, leading to this "controversy" and so many of these follow up videos
it is a trick puzzle to throw people off track (mislead us). Everyone knows that the speed of electricity is near-c (not at c, but at 0.9c) meaning it indicate propagation inside the wire medium but then he created this trick puzzle to show us that signal did move at c & also jump across wire to mislead us into thinking that signal move outside wire thru fields...
++EEVBlog. The key to remember is that All electrical energy is transferred through EM fields. So for a pair of very long super-conductor wires transitioning from "off" to "on" there would be a "pressure-spike" in the EM fields radiating out at the speed of light(ish). This would go out in all directions with power moving preferentially through the wires. The EM field between the wires would be modelled as capacitive coupling between the wires with the amount of capacitance tending to infinity as the wires get longer. So the light "turns on" about 4ns after the switch is thrown because of capacitive coupling between the wire, but it'll take a lot longer to ramp up to full power. The DC state is the same as AC at the physics level, but the "transients" in this case are individual electrons being freed in the chemical reaction so the hypothetical "pressure-spike" is unmeasurable.
@@Darxide23 given he’s acknowledged that it was a deliberately misleading puzzle designed to trick people, then I think you’ve been a bit unfair here. The correct answer fyi was none of the above - the light would always be on, because he stated clearly that it would turn on from any amount of current, so that light could never be off. Electrical drift across the switch would make it brighter before being thrown.
@@Darxide23 my theory wasn't that he wittingly trick us but my theory is that he got tricked himself; after he won that $10k bet for a car that unintuitively use propeller as sail he made a challenge for anyone to deliver an "unintuitive science idea" for that $10k money ,and most likely he fall for this puzzle himself and someone else won his money. He fall for these theory because based on his video I can see he likes to prove people wrong so when people are critical of this theory most likely it made him go head on toward the theory (as a challenge) rather than taking it as a red-flag.
As far as I know, the first transatlantic cable was just single wire. I believe most of telegraph connections by then were single wires with voltage applied against the literal ground. The communication did not exactly rely on closed circuits, rather on measuring changes in electric potential in the wire against local baseline. The point is, Veritasium was trying to convey the perspective of power being transferred via combination of electric and magnetic field through the space. It's not wrong, it's just a perspective we use to explain the world because it is often useful. But explanation what happens in his experiment or why the transatlantic cable was a failure does not need such perspective and can be fully and sufficiently explained just using usual terms like induction and capacitance (resistance was in his thought experiment ruled out, except perhaps the lightbulb). I'd even say that this power perspective is only useful for stable conditions and totally does not explain why there appears current through the lightbulb right after we turn the switch.
The real way to draw a pair of wires is as a series of resistors on each wire, then between the resistors you have capacitors between the pair, if you have an outer screen, you can then draw capacitors from each wire to the screen Effectively you end up with series resistors and parallel capacitors along the length. a bit like a pi filter. Yep, there's all sorts of problems with multiple substations, where i worked we had 5 substations on the main site, one of the cameras on the CCTV system wouldn't sync because it was on a different substation, the cure was to install an isolation transformer in the video line. Screened cables should only be grounded at one end (the originating end) We had data between several buildings, the cable had a sceen and armour, when it was installed we had problems everytime there was a thunderstorm. they had grounded the screen to every cabinet, and not used the armour We corrected it by grounding the armour at every cabinet, ground the screen at main control, then looped the screen through each cabinet conneecting to the next screen, but insulated from the cabinet And as belt and braces, installed crowbar circuits on each cabinet's data lines
What about capacitor leak? Surely the capacitors should also have very high value resistors between them too? Man this gets complicated... it's almost as if "conductor" and "insulator" are idealised terms, and what the actual universe gives us is more of a gradient, and circuit diagrams are a simple description of what matters to achieve a certain result, and not a recreation of all aspects of reality within the device... huh, who knew?!!
you forgot: Also a series inductance. because electrons have elasticity. The current can't turn on instantly. Than you have the RF cable / transmission line model. And basically any frequency (even just 0.1 Hz) will behave like RF if the cable is long enough for the wave to show. (Otherwise you would just look at a VERY "zoomed" portion of a ( most likely sine) wave)
@@TheRailroad99 Depending on how you derive the DC, you could get ripple which would be ulttra low frewuncy rf i guess Even if you derive the DC from a battery, there could be induced RF, or interference from the corrosion of the battery terminals. Have i gone deep enough ? :D
"the real way to draw a pair of wires" - yours is not the real way either. Yours is still an extreme abstraction of what's actually happening. It still fails to adequately explain what is going on, and uses concepts that themselves are also just abstractions. That's not to say it's a bad model, but don't go telling people your way is right, when it isn't, it's no more valid than other models.
I certainly disagree with Veritasium. Take length matched PCB tracks for example. If Veritasium is correct, the data would flow directly from the transmitting device to the receiving device, and mess up the timing. However, that's not the case. He's being vague when he talks about the bulb being 'on'. I can accept that there would be a flicker due to a surge in current by the switch, but It wont reach a stable continuous 'on' state until the current reaches it.
I think that Veritasium was a little bit vague on what he meant by ‘on’ too. There is energy flow at the bulb nearly instantaneously ( 1m/c s). But this is because of the transience capacitance between the transmission. Given that this would go as the dc circuit reaches steady state and the current becomes stable. All of what he said is technically true but it’s very contrived setup
That's the correct take. Veritasium conflates transient effects with the steady state situation. There may some energy be transferred directly trough air by inductive and capacitive coupling and electromagnetic radiation, but the bulk of the energy is transported along the wires once the circuit has settled into steady state DC. He is correct that the energy is in the field outside of the wires, but it has to follow the wires closely for DC.
Energy doesn't travel in wires, and the filament of the bulb is a wire, which means the bulb never turns on. We know this to be true, which is why no light bulb has ever been seen to be working, and anybody saying otherwise is in on the whole thing.
@@annoloki The filament is a wire with resistance, which means energy flows from the field outside the wire into the wire and is converted into heat. If the bulb is connected to the source with wires without resistance, then the energy flows as field energy outside these wires and they don't get hot.
@@Theo0x89 Prove the energy flow you are talking about. How do static electric and static magnetic fields outside the wire cause energy to flow inside the wire?!
The undersea cable sounds like a problem Oliver Heaviside worked on and Kelvin's transmission line analysis. Heaviside's development of complex numbers and vector algebra was fundamental to the understanding the delay associated with capacitance and inductance in the cable. It (Telegrapher's equations) also was the precursor to the Shannon-Hartley theorem of bandwidth vs data rate.
Local ground potential differences can be a big problem on the rail network as we often have multiple independent electrical systems operating at both low voltage 650v AC (for signals) and high voltage 25kv AC for traction or 750v DC in areas with 240v residential power. It's not uncommon to see gates sparking where the hinge side is on the rail network earth and the latch post on the national grid earth. It's a bigger issue with access steps where the handrail may be grounded at one end and have a long run to where you step onto them.
Yes, I would agree with that. I commissioned a high-impedance bus zone protection scheme for a double 33kV switchboard at a 275/33kV grid substation, which also accommodated a 25kV supply to Network Rail. I found I was getting spurious operation of the neutral check relays on the busbar protection and there was often 'standing' current displayed on the relays. I had a theory - which I was never able to substantiate, unfortunately - that the spurious NCHK operation occurred at the time a train passed the substation. I was able to prevent the unwanted relay operation and still have a working protection scheme but never managed to prove my theory.
Veritasium’s example was an outlier from which it is stupidly inappropriate to generalise. His circuit geometry is a basically a pair of big fuck-off aerials and so is dominated by transmission line effects. For any circuit of normal proportions, all signals are transmitted along the wires (and electric engineers will specifically design to *avoid* internal EM transmissions).
VT is correct in deducing that the Poynting vector aims directly from the battery to the lightbulb. The thing is: in his setup the battery side and the bulb side effectively work as coupled antennas so when he connects the battery there’s an instant disruption in the electric field and that is transmitted by the wire ‘antenna’ one meter across to the ‘antenna’ of the lightbulb, transmitting a ‘signal’. However quite some time shall pass before the full flow of current will arrive. And indeed the full current flow *must* ‘explore’ the full characteristics of the circuit: what if there’s a 1 mega-ohm resistor half a light second down the line? When would that come into play in VT’s scenario?
Antennas are coupled AC. A wire stuck on the end of a battery does not act as an antenna. A single rising edge travelling away from the battery would at most cause a single blip on the other wire, but it would also be travelling away from the bulb. I say "at most" because it can easily be dissipated as movement of particles in the air.
@@annoloki But a signal propagating *away* from the bulb and eventually meeting the signal propagating *away* from the battery midway along the conductor is precisely what you’d expect in my scenario.
@@larslindgren3846 No. The Power going to the bulb *_IS_* low until that point, and then just doesn't increase much if there is a resistor. The only reason he gets away with his "lights almost instantly" claim is because he specified the "the lamp will light at ANY current" which is not even possible in theory. In a much more realistic scenario with a real 7w LED lamp, I calculated that it will reach 80% of its nominal brightness after about 7 MINUTES and 30 seconds, which is when most of us would probably accept the phrase "The light turned on." Before that, of course the interactions in the circuit do indeed start like he says and there will be a tiny interaction after 1m/c seconds. Whether you talk about these interactions as radio waves or electric fields or whatever doesn't make that much difference in the end. There are several effects at work and can be modeled in different ways to get the same results in the end.
It's not just directly from battery to lightbulb. It's in all sorts of paths, including EM energy from other sources (so long as energy is neither created nor destroyed). The key takeaway that got lost in the irrelevant noise of Derek's examples is that energy doesn't flow through wires. It's also not just in coupled antennas, which is one reason that example was so terrible. It's true in a perfectly circular circuit, too; the energy traveling from battery to bulb does flow faster than the charge is passed down the wire, but he's also wrong about the energy getting there first - the charge has to propagate through the bulb for the poynting vector to direct the flow of energy into the bulb. Really it's a terrible example with all sorts of confounding factors.
I've kind of been waiting for your input on Veritasium's video. I suffered the very problems you refer to, e.g. how would power transfer along a SWA, or screened cable, how do we only get a shock from the core of a conductor etc. And the comment about not burying cables due to losses - when cables are regularly buried! His video just didn't seem to tally with everyday experience. Glad you had something to contribute on the matter.
Just to chip in on this - the electron doesn’t know it’s surrounded by a screen - it will produce its radiation because it has too, when it moves. The radiation will affect the next electron in wire because it has to, when you place an electromagnetic field over an electron, it has to start moving. That you’ve wrapped an em shield around the wire doesn’t matter, you have just confined the relationship to within the wire but the EM radiation is still where the energy actually _is_ .
I remember that whilst attending meetings of the Rugby Amateur Transmitting Society (RATS) when it used to be held at Rugby Radio Station, now sadly demolished, when certain members used to use the trick to light up the carpark by merely placing a fluorescent tube in the gutter of their car, and keying the rig in CW mode.......Magic 😊 Regards, Keith (G4TDA)
At our last house, we had to call BT 3 times to stop the crackling on the phone line (each time getting the dire warning that we would be charged an extortionate fee if they didn't find a fault). Local cables were changed, terminals, tightened, but It finally turned out to be galvanic action on terminals in a remote cabinet. Wasn't very impressed with the fault finding, but don't have that problem in our new home- now have full fibre installed. Just waiting for Veritasium to say that our internet signal is not actually coming through the fibre optic cable! PS. As told during my days in the CEGB, Overhead lines are strung from Transmission Towers, Pylons are for mooring Airships! (BTW, the original definition of a pylon was an Egyptian Arch)
I think EEVBlogs had a good take, In short there is the school of Physicists and the school of Engineers. Physicists usually have a grasp on how it really works, Engineers have a better grasp on how to apply it in the real world. I think we, watching your videos, are mostly of the engineering school of thought, but Veritasium is from the physics school of thought.
From the perspective of the school of physicists: by Veritasium's definition the bulb would be "on" even before the switch was closed. This is because Veritasium defines "on" as happening when *any nonzero current* flows through the bulb, no matter how small. Johnson-Nyquist noise, created by the thermal motion of charge carriers, constantly creates tiny, fluctuating currents in anything that's not at absolute zero. So the lightbulb *always* has some tiny amount of current flowing through it, both from this and from incident EM radiation from the rest of the universe, and is, by their definition, always "on".
@@drdca8263 That definition still has problems. Johnson-Nyquist noise is a random process with a roughly Gaussian amplitude distribution for any finite bandwidth. As such, its instantaneous amplitude has some probability of being arbitrarily high (or at least, up to a height at which the underlying model becomes invalid). So, if you set some reasonable value of "expected while switch is off", there will be some instant, if you wait long enough, at which the bulb will spontaneously be "on" by that definition even as the switch is off.
@@probably_someone000 by expected value, I meant the expected value of that probability distribution. Not comparing the actual value in one case to the actual value in the other case, but the probabilistic expected value in the one case vs in the other case. (I suppose before you said it was Gaussian I didn’t know that it had a well defined mean, but it seemed a reasonable assumption) Edit: of course, a device can’t activate when an expectation changes, so I’m just talking about defining an amount of time, not describing something that could possibly be observed to happen at a given time) (Edit2: so, to make the description more concrete: suppose that for each n from 1 to 5 * 10^9 , you run, a bazillion times, two versions of the experiment, one where you flip the switch and one where you leave it unconnected, and in each case after n nanoseconds, you measure the current where the “lightbulb” would be in the original. Then, you take the average over all bazillion trials. Then, compare which average is higher. As you take the limit as “a bazillion” goes to infinity, what is the first value of n such that that no larger value of n had the one with the switch not flipped have the higher average? This many nanoseconds is the snout of time I mean.)
One the best vids you have done! To expand on theatre lights, they usually use DMX as the data transmission type. DMX uses a differential signaling standard called RS485. The switching of polarity is great as when the two signals are combined at the dif amp receiver, in phase noise is cancelled out using common mode rejection. The same applies to balanced audio as well. Something so many in my AV industry take for granted. A fire and forget transmission type, so I wouldn't rely on this for mission critical events.
I think VeritasIamNot did a very good job of making click bait, ensuring that lots of people would interact with his video and everyone would be talking about it, thus driving the algorithm higher, by being "accurate" but leaving out key details. For instance, most of what he talked about and made sound like it's stuff people don't know about, is actually well known in all Transmission Line Theory, which everyone from RF engineers to PCB designers have to take into account. And his entire example had nothing to do with the light year length of the wire, but rather the 1 meter spacing between the two sides via capacitive and inductive coupling, which happens right next to the battery and light, and doesn't go to the end of the wire. In other words, the results would be entirely different if it was a loop rather than balanced transmission line on spacers. Also, what he said about the nearly instant current flow would not have been enough to illuminate an incandescent light bulb, that would have to wait for the current to flow along the entire length of the wire, but what he was talking about was something that could only be seen on an oscilloscope etc, and was just that initial low level coupled charging of the capacitor, and not really the current from the battery that could light a light bulb. So yes, he was pretty full of it, and knew it! Lol Eevblog had a pretty good look at it.
> what he was talking about was something that could only be seen on an oscilloscope That's the key thing that confused engineers. Someone said that a dynamics question that does not mention the time of the sampled result is just not a good question.
My best understanding (having had a basic electronics indoctrination 40 years ago) is that electricity behaves like heat. Electrons get excited, hit nearby electrons and so on. The ability of a given material's electrons to get excited defines the conductivity of the material. I know about EM radiation, but I can't understand how so many people struggle to apply a scale to the concept. I mean, it's clear that electricity comes with electromagnetism, just like, say, a soldering iron will *_also_* heat up my lab. This doesn't mean I can melt solder from a distance or that I can keep my house warm with an iron. Veritasium's "iron" has infinite power and is used on a special kind of solder that can melt at room temperature. See? The solder melts with the mere *thought* of using the iron! :D
Thank you - it's the AC component that starts to manifest things outside the wire. This why you can't easily measure DC current with a clamp-on meter like you can with AC.
Hey, uhm i'm a layman with a little knowledge from back in my radio enthusiast days. I remember studying the effects of propagation, dampening and all the weird stuff concerning antennas. I specifically remember that thing called "Verkürzungsfaktor" aka nominal velocity of propagation. I mean pointing vectors (is that the correct spelling?) all neat and fine, but there was so much more to consider back then. I don't know if physics changed while i was looking away, but from what i remember is that you can have a potential differential anywhere you want within the limits of relativity at any time you want, but power transfer is a different can of worms. So yes, that lightbulb would see a different potential, but it would take time for the circuit to match to the demand that voltage would bring. Like you connect a bulb to mains and measure still 230V, connect the same bulb to a AAA battery and you measure my IQ ;-P Long babbling short it's a mismatch in internal resistance/impedance of the conductor/breakdown of voltage due to a quasi short circuit. All i wanted to say is that i thought the Veritasium video made too many omissions to to convey a fringe idea that does not include the change over time in a system. No delta t anywhere. And actuating a switch provoke some delta U, right?
Poynting. John Henry Poynting. Nothing to do with pointing, which is confusing. Also Oliver Heaviside discovered the concept, and also discovered the Heaviside layer in the atmosphere, which is another thing that sounds like a physical description but is a person's name. Electronics has loads of confusing things like this. For examply the Early Effect. Nothing to do with being early for anything, it was named after James Early at Bell Labs. Similarly, the Gunn diode. And the D.C. Power lab at Stanford University houses the artificial intelligence lab, and named after a person, nothing to do with electrical engineering.
In the description of Veritasium's video, there is a link to a couple slides authored by the Physicists he talked to in the video that delve into the change of voltage over time, I think those slides talk about what you're mentioning but nevertheless, not an EE by any means so I may be mistaken.
I'm so glad you made a video for this. I watched that video and it blew my mind. As someone who is still new and learning as much as I can, electricity and just what it is, is really hard to wrap my mind around. I understand the different theories, electron vs conventional, but it just doesnt make sense in my mind. Thinking of it in a different way such as fields or magnetism helps give a different perspective to help my puny ape brain. Thanks for all the videos Clive, you've helped me develop a healthy hobby that isnt slowly killing myself like before. Cheers buddy.
I knew Derek had pulled a thunderfoot and was talking outside his own expertise with authority when not informed correctly when A) "The light turns on in 1/C seconds because poynting vector" when the lightbulb would have no current though it so the cross-product of its own vector would be nothing initially, so not absorbing any energy. The energy coming out of the battery would be charging the wires, and some being radiated into free-space as an RF burst/EM wave. B)The 2 light-second-long loop would be tested for continuity instantly, which is obviously naughty and not how physics works. (I.e. put a switch 1/2 light second out at the end of one arm, when you connect the battery, it needs to be determined if that switch is open or closed before DC current starts to flow, so its at least one second before that information (I.e. the edge of the voltage wave on the wire) comes back to you.
"Pulled a thunderf00t" is the best I've heard in a while. Some of his videos are informative but lately he seems to think himself an expert in every field.
There is a radio station I listen to that gets inference when I plug my laptop cord in, when I turn the rear window defrost on in my car, and when I use certain electrical device within a ten foot diameter of a radio. It happens on multiple radios multiple sources of inference that shouldn’t be emitting radio waves and occurs constantly. It is only that station, other stations from the same broadcaster are fine. Edit: It is FM 92.1 incase anyone was curious.
Thing is, Derek says "bulb lights as soon as **any** amount of energy reaches it". This is the trick. And now we have to separate things discussed in this video: - The initial pulse you get in DC via the capacitor analogy (the two wires being the capacitor) is super tiny, not barely enough to light the bulb if you don't apply Derek's "trick". After that pulse we have to wait to the "real" current of energy reach the bulb. - Second point - which has nothing really to do with the above, but is just an interesting quirk from the physics formula - is the Poynting vector, which simply shows that Energy flows into a wire (with resistance) (the "wire" can also be the bulb), from the electric field. There is not really a reason to mix those two things together in one video. The first point is basically a question about how a radio antenna or a capacitor works, the second one is some obscure (and in reality useless) fact that arises from the formula. His video is misleading and puts two topics together that don't need to be in one video. But the good thing is, it makes people think. Although they now think that (all) the energy just goes through the air which is totally wrong. Now the real question would be, at what point does the bulb starts taking the "full" amount of energy (to make it light in real life and not just with his "trick") from the field.
SWR meters illustrate coupling well. Also, my old RF teacher made me understand how "energy" works. Think of every time you charge up that big electrolytic by connecting it to a DC supply. Now, make one plate a round disk and the other plate a rod sticking up through the middle of the disk. Still a capacitor, but now it's an antenna... That'll charge up just like the electrolytic, but now it chucks out a huge EM pulse while it's charging. Current through the air...
4:50 - sunlight being part of the electomagnetic specturm = I think Veritasium covered it. A light was shone through a prism to split into visible colours and the temperature was recorded by each colour of light. A control thermometer was set just outside of the red wavelength light but it was found to be the warmest. Infrared was discovered.
Here in New Zealand there is a high voltage underground feeder that runs at 220kV and it has reactors at each end to deal with the capacitance of the system.It only goes about 20km, but the capacitive effects are large at that voltage
I work in high frequency RF. Veritasium is completely wrong and we can prove it easily by measuring the electrical length of a RF cable while physically moving the far end. Take an impulse generator (can be as simple as a charged capacitor), oscilloscope, and good length of coax cable - doesn't need to be much, 15 ft would be enough for a 50 MHz scope. Connect one end of the cable to the oscilloscope plus signal source and short the other end (leaving it open also works, but shorted will be clearer on the scope). When a spike is injected into the cable, it will propagate down the cable at a little under the speed of light, hit the far end, then bounce back to the start. You will see two distinct peaks on the scope - one when the spike first enters the cable, and one when it gets back from the far end. Now, move the far end of the cable relative to the oscilloscope and see if the distance between the peaks moves. I will put my entire net worth on the result being No Significant Change. We have cable which is specified not in physical length but electrical length - wavelengths at a specified frequency - and this is one of the ways it is measured.
I also love Crystal set Radios probably could do with better Earth as I tend to use radiator pipe. When I was younger I made a capacitor/ Leyden Jar out of large plastic cup for Dice and foil and taped thin aerial in middle and charged it up with static on screen of my CRT Television in my bedroom enough that could feel charge in Air / ozone enough to make my Cat wake up and leave my room, and I got scared was too much so I touched it against the Radiator in my Bedroom and there was a spark and at same time a bang downstairs as it blew the water pipe under the kitchen sink clean off the wall where metal pipe was connected to a plastic y shape pipe junction and flooded the kitchen as water was pouring out so fast, I was in my Bedroom at time so my parents thought it couldn’t possibly be anything to do with me, they still think that to this day.
I saw that he that Veritasium video, and remember thinking that he is increasingly looking for science to explain a hypothesis - instead of the other way around, as it should be. His explanation of his hypothesis was pretty simplistic, while your analysis of it introduced some complexities that were noticeably absent in his presentation. I like your take on the real world concept of this much more than I'm comfortable with his simplistic assertions.
Watch IBM's 'A boy and his Atom', to see actual pictures of atoms (fascinating). Veritasium's thing only works because of the changing fields at the moment you activate the switch (turn on transient), so it does end up as an AC /RF problem in a way, a transient contains multiple frequencies (listen to an AM radio while turning on a light).
@@JoshuaNorton Sorry, I have no idea what passive-aggressive means, other than it's something spoken by 'woke' and the geometrically patterned ice crystal brigade say. I'm never bothered by someone being right; however I do think that people with a small knowledge of those type of subjects will only be confused for the sake of a 'click-baity' title, and that does bother me.
Science Asylum's older video on this topic was a lot better than Veritasium's. It is theory, but the context where the "energy is transmitted through fields" thing makes sense (is actually useful) is quantum electrodynamics. Derek got sucked into a click-baity toy problem which really just doesn't quite work. PS: Medhi (ElectroBoom) has a great response video to Derek's. Well worth the watch IMO.
Electricity and magnetic fields are interconnected that why they can be explained by an electromagnetic wave. The theory exposed by Veritasiom does not negate the one you exposed. That theory is a further explanation of the how. In the model that you initially explained where electrons are pushed towards one end of the wire. For that to happen you need to transmit that push from one end to the other so it is like electrons pushing electrons pushing electrons. That can be visualized as a wave exactly as a wave on water pushes molecules in one direction. So you come to the conclusion that the flow of electricity is a wave. Furthermore, you are certainly aware of the connection between electricity and magnetic fields as you certainly know that electricity going through a wire always cause a magnetic field (that is the principle of electric motors). A variation of a magnetic field can also cause induced electricity in a wire (that is the principle of an electric generator). So a "wave" of the electricity will cause a "wave" of magnetic fields and vice versa. Therefore, you come to the conclusion that electricity is an electromagnetic wave.
Electricity is NOT an electromagnetic wave. Steady state electricity does not emit any electromagnetic waves. For a charge to emit electromagnetic wave it must move with an acceleration.
Is it a wave push - or the moving of one electron into a space in the next valent or co valent shell which moves to the next space, now it needs to be asked why that movement of electrons - by attraction or the 'gravitational pull of excess of electrons trying to even themselves out - creates a magnetic attraction. Note that the magnetic field is fairly weak of itself and is only increased by the presences of a suitable material like iron (or better 'rare earth' minerals.
Veritasium's video is confusing and wrong in a number of places that have been discussed elsewhere, but bigclive brings focuses on a bit of the video that has been less discussed. Veritasium's major fault is he dies imply that traditional electrical models are wrong ”lies” as he calls them! The big confusio everyone seems to have is the distinction between charge movent and energy flow. These are two totally different (albeit conne ted) phenomenon. Your wrong when you say waves push particles along, it's the wave that travels not the particles (wether it is a wave in water, air or an electromagnetic). EM waves can move outside of wires, but that does not mean the movent of charge does not occur insude the wire. They are two different things.
@@andy_taylor I know that particles are not moved very far by waves in water. That is exactly why I used that example. The wave in water is the one carrying the energy while the particles only get slightly pushed in one direction each time the peak passes them. In the same way, the electromagnetic wave is the one carrying the energy in a cable while electrons will only be pushed very slowly
Dave over on EEBlog is the best I've seen. The key to remember is that All electrical energy is transferred through EM fields. So for a pair of very long super-conductor wires transitioning from "off" to "on" there would be a "pressure-spike" in the EM fields radiating out at the speed of light(ish). This would go out in all directions with power moving preferentially through the wires. The EM field between the wires would be modelled as capacitive coupling between the wires with the amount of capacitance tending to infinity as the wires get longer. So the light "turns on" about 4ns after the switch is thrown because of capacitive coupling between the wire, but it'll take a lot longer to ramp up to full power.
Thanks, this explanation makes the topic much clearer for me. None of the videos really made it clear to me that the phenomena was an just an initial “wireless” EM coupling, followed by a “proper” circuit which stabilised much later. No magical information transfer faster than the speed of light; no exotic effects beyond the standard EM formulas.
@T.J. Kong Poynting vector exists where the magnetic field and the e-field exist. It's saying that the flowing electrical energy IS the fields outside the wire. Yes, duh, since in coax, all the RF energy is flowing in the dielectric, not inside the metal. What people simply won't believe, is that the same is true at all frequencies, all the way down to DC. "Wave energy" and "RF signals" follow the same physics at MHz, at 60Hz, and at DC. A 2-wire line can send field-energy to an antenna, or to a resistor such as a light-bulb. And there is no special magical frequency where "RF" becomes "AC," or where "AC" becomes "DC." (What we call "DC" is simply a square transient which lasts for minutes rather than microseconds. It follows the exact same physics as the RF pulses.)
@T.J. Kong It's easy to light the "ideal" bulb used in the thought-experiment, and even a real LED should light just fine: a few volts at 4mA for an entire second, until the main 12V signal makes it back around the loop. Actually the "transient" is a genuine DC step which starts immediately, then runs continuously for an entire second. So yes, a "brief transient" can be many seconds of pure DC, if we're dealing with millions of miles of superconducting coax or twinlead. (The people claiming that it's a spike, they incorrectly employed ten-foot cables in their simulations, not the thousands-miles cables given in the actual thought-experiment. OF COURSE they get a spike. They made an illegal change, and created a Straw Man to attack.) In other words, if our transformer coils are 100,000 miles wide, and spaced one meter apart, then the coils are coupled 1:1, and we can send DC through the transformer (actually it's half-Hz square waves, pure DC for one second.) That, or just replace the long 2-wire cables with their Zo resistor. If they were coax, it would be 50 ohms. For 5mm cables spaced 1000mm apart, it's around 700 ohms (times two, since there are two of those placed in series with the bulb.)
It's also important for people to realize, production value doesn't make you right. People that trust their own intellect too much tend to screw up like Veritasium. You'd be surprised how many "physicists" fail to disprove Flat Earthers simply because they don't have the actual ability to work out the scientific results from the data. In Richard Feynman's biography you'll find some examples of physics book authors, and PhD students, failing in grasping the very thing they were regurgitating with authority. Veritasium would not have embarrassed himself so much had he asked somebody with actual training on this field for feedback.
@@dkosmari No physicist can disprove a flat earther because they don’t have a physics model to disprove - they either try to disprove one of our current models or draw a map that can be disproven by pointing out that their distances in the Southern Hemisphere don’t match reality.
@@PippetWhippet Flat Earthers don't have actual maps for a reason. Physicists should have basic grasp of geometry and topology, at which point it's trivial to understand you can't flatten a sphere without stretching and tearing. Any Flat Earth map will have conclusive pair of points that are extremely separated in the map, but close together in the planet.
Having cables under ground is a reall issue. They have to be calibrates with capacitors to remove the inductive load of the ground. This take a signifcant amput of power even for short runs. This is the main reason power cables is over ground. For DC cables this is not issue. So dc cables can go under ground, but they have a other problem. Joining them. Under sea cable is made in one go. Ground cables have to be joined in field, limiting the voltage to 350kV. Now there is some part that is absolutly corect with veritasiums statment. The issue is that he uses a dc source. If it was a ax source and that amout of cable. It would basically just be a huge antenna. While the energy would reach the lamp in one meter distance, the voltage would only be a fraction.
When working as a service engineer in London way back when Parking in a multi story .a little trick we found ( by Accident) when returning to the van , with our tools was to use the (Metal) sack barrow with our tool boxes on to trick the sensor at the entrance to pop out a ticket and lift the barrier. This allowed you to drive your van out and not be charged at the exit. Or pay a minimum charge .I don't know if that would work in to days technically world
Thanks for that, Clive, I now understand the meaning of the word, tangent. 😂 Seriously though, it's amazing how well our models fit with electrical and electronic circuits. It's interesting to pull back the curtain from time to time.
For the "electrons move opposite of conventional current", I have always though about it that since electrons are negatively charged, when they flow one way, the current moves the complete opposite way (aka, what the negative sign does for pretty much anything) Probably not theoretically sound, but it's how I committed it to memory.
I’ve always remembered it as holes flow in conventional current, electrons flow in electron flow. Holes are just where electrons used to be, a made up particle.
I honestly thing Derrick made his video knowing it would stir up a hornets nest. He saw what his video about the sailing machine, and then Electroboom vs. Steve Mould videos about the chain fountain effect did engagement/views wise for the science and engineering communities here and found a way to turn it up to 11 with his video. I am expecting him to admit this in a new video any day now.
I dunno, his next video on bike riding was also complete rubbish that only applies when the person on the bike stays bolt upright, and turns away from the direction of turn to cause the lean. I watched my own turning after watching his video, and saw no such effect, because it's my primary mode of transport, it's intuitive for me to address the lean by shifting the weight from my body, which you can do far more safely in a narrow lane than beginning with a turn in the opposite direction. I think he got a few things right, and we're now seeing the "return to the mean" of getting things seriously wrong that makes his videos average out to be okay, while he's probably forgotten that being right on the last thing doesn't predict the outcome of the next thing.
I was taught to imagine current as hole flow. Electrons (have negative charge) are repulsed by the negative voltage and jump from an atom to a hole in a nearby atom leaving a hole (the atom missing an electron has a positive charge).
Way back when (1977) I was learning electrical fundamentals, I was given 2 theories on electrical power flow. 1: Electron theory, Electrons move from negative to positive potentials. 2: Hole theory, When an electron moves from one atom to the next, it leaves a hole behind to be filled by the next electron. With the holes moving from positive to negative. Both theories have them moving at close to the speed of light due to that when one electron is moved from the first atom to the second atom, an electron from the second atom is pushed to the third, and so on to the fourth... I think that what Veritasium was talking about, is the secondary effects of those electrons flowing.
Electrons and holes do not move very fast at all, only a handful of meters per hour. Their effects, however, move quite fast. Consider how fast a wave can travel across the ocean, but really most of the water stays in place, circling up and forward and down and back as the wave passes. Another analogy is a long line of people waiting to enter a restaurant. Imagine the person at the end of the line gets impatient and shoves the person in front of him, who shoves the person in front of him, and so on. The shove will move forwards through the line and reach the doors long before the last person in line.
It's not secondary effects. He (Derek) explained Poynting very badly, which is a huge part of where the controversy is coming from. Poynting describes the flow of energy, not electrons, and in all cases the energy flow is at right angles to both the flow of the charge (electrons) and the direction of the magnetic field (which are right angles from each other). Energy does not flow along the wire, it flows through the EM field, and it does so at the speed of light. Not _some_ energy, not radio waves or incidental amounts of energy from inductive current. All electric/magnetic energy.
On the original video it's really a bit of a trick question. He sets up the problem like we are assuming a basic DC condition but the "gotcha" is that he has then applied AC theory. As soon as capacitance and inductance is brought into the equation then what he says is technically correct but in a really round the back sort of way. Conventional Current for me thanks.
I believe Derek Muller of Veritasium IS RUclips. His 20 minutes video caused so many airtime by other youtubers, so many videos made to confirm or counter his views, sold so many ads. It must be that way ... Derek, give me that Dislike count back!
Correct, Clive. For most practical purposes as it applies to electrical/electronic engineering applications, skin effect is insignificant and conventional current flow is used. Skin effect doesn't occur at DC, because there is no electro-magnetic field created. Transmission lines are impedance matched to minimise loss. At 1GHz and above, waveguides are used as skin effect does become significant. You can see a wave guide at work, by looking at the ends of a live optic fibre cable, since light is part of the RF spectrum.
Your thoughts make a lot more sense to me than Ve's video. I know his whole thing is being smarter than everyone else (and maybe he is and he's right) but the issues you brought up makes a lot more sense, And comes from real world lived experience, not theory. If you asked me who I wanted to do a critical wiring job; a theorist or an experienced electrician, I'd go with real world experience every time.
The parasitic inductance and capacitance you mentioned are distributed along the length of the cable, as is the resistance. That is why we have transmission line theory to figure out the effect they have. They were a problem for telegraphy (and later telephony) before we had transatlantic cables. Their effects are mitigated, to some extent, by adding inductors. From memory, I think Heaviside played a part in that.
0:40 Has anyone seen an electron? What does "see" mean? Optically? Well yes and no. No in the sense that electrons are too small to be individually resolvable optically. But yes in the sense that the reflections from objects that make them visible are essentially due to the interaction between the incident light and the electrons of the object. But beyond that answer, what we know about electrons comes from many types of experiments that indirectly reveal the nature of electrons (and atomic scale particles in general), some of which translate into commonplace devices where the electrons behave in a well-understood fashion, such as in vacuum tubes. And of those, the CRT is a particularly visual example.
In another sense, electrons are the _only_ thing we ever see. Every photon your retina has ever captured was emitted by an electron, absorbed by another electron, and then shuffled into your brain by a series of other electrons. It's all electrons.
@@oasntet Hahaha -- you have a point! Though actually it is possible generate visible-wavelength photons from accel/decel of other particles, but most that we see are from electron transitions (well, electrons in conjunction with host atom).
Oh Clive, this shows the difference between engineering and science. The science is consistent regardless of any one dimension (e.g. frequency), so asserting it doesn't (may not) work outside the familiar radio (or higher frequency) range is starting to encroach on flat earth territory. Much of the familiar world, and the simplifications we make for early learning or "good enough" for everyday engineering become extremely counter-intuitive when you dig deep enough; counter-intuitive is not wrong if the evidence supports it - we just have to change our understanding of how the universe is actually working (to more closely understand reality).
Fluid mechanics taught me that simplifying assumptions are sometimes required to do anything useful. While technically the answer is always just: 'solve the Navier-Stokes equation' that might not even be mathematically possible. You need to use simplifying assumptions like laminar or turbulent flow, steady state or not, etc. If you ever did simple optics calculations you probably used a similar idea. Most of the equations use the small angle theorem where sin(x)=x to make them easy enough to solve by hand. It's pretty much true for small angles, so it works and you get to cancel out some nasty bits of the full equation. So basically, Clive is doing this. The science may say that it technically applies, but his intuition is that it is not a significant factor until you get up to higher frequencies. As far as I know, it does not apply in DC steady state at all. It is important, by the way, to always list and justify your simplifying assumptions. Just like drawing a Free-Body Diagram with axes and force directions is important in normal mechanics. Tl;dr: a correct equation that cannot be solved is useless. Simplifying is sometimes vital, and one of those is that you can ignore the EM effects of 12V on a wire 1m away for a low frequency circuit.
I don't think that Veritasium's theory is wrong. The Poynting vector is a well established quantity in electrodynamics and there is broad consensus among physicists that the Poynting vector does indeed describe the energy flowing through / transported by electrodynamic fields. Therefore the theory, that the energy does actually flow through the fields around wires instead of the wires themselves is in agreement with dozens of electrodynamics textbooks and is a direct consequence of Maxwell's equations. Arguing against this theory would mean to argue against Maxwell's theory: Good luck with that! However I absolutely agree with you, that the examples mentioned by Veritasium were kind of weak and did not necessarily support his theory. As you have quite beautifully explained in your video, there are other, simpler explanations for all examples mentioned by Veritasium. Especially the fact, that there are underground power lines as well, seems to discredit his reasoning behind overground power lines. However, just because his examples were weak does not mean his theory is wrong. Again, his theory is based on well established and undisputed electrodynamics. It stands on such a solid theoretical fundament, that the lack of good examples is not enough to discredit this theory. At least in my opinion.
V's theory is poorly thought out and even more poorly described. As presented both the lightbulb in the circuit and an unconnected light bulb would be lit at exactly the same time due to the capacitive and inductive leakage as the circuit pulses on closure of the switch. Upon reaching the steady state the lightbulb not connected to the circuit would no longer be "lit" yet would have those field lines not passing internally in the wire also passing through it. This demonstrates clearly that the internals of the wire are having a massively larger effect on power transfer than the external fields that also pass through the unconnected bulb.
Electroboom made another "debunking" of the presented theories; it sounds very reasonable. Main issue is the fact that Veritasium uses a fictional light bulb, activated by the slightest of currents. There is *some* charge moving through the bulb, but depending on the geometry, the initial current spike from the transmission line would be extremely small. It would only turn on fully after 1s, as by that time, the electron wave has reached the bulb, creating the magnetic field required to transfer the full energy. Before that, the coupling is based on capacity between the two wires, which is tiny (two wires, 1 meter apart in air have almost no capacitance between them).
To get an EM wave, you have to accelerate an electron. That happens for an instant when you first flip the switch on a DC circuit, and it happens every time the electron changes direction following bends in the wires. It happens every time the voltage changes and the drift velocity of the electron changes. But for a straight wire with a steady voltage and current, no EM field is created because the electrons aren't changing velocity. To generate a constant EM field, you need AC where the electrons are constantly accelerating (deceleration also counts as acceleration). Resonance with the wavelength also enhances the effect quite a bit. That's how antennas work.
I think the biggest problem for undersea and other long cables is that the cable posesses series inductance and capacitance between conductors and/or ground. This forms a low pass filter and the leading edges of the data pulses get slowed and the pulses can no longer be measured. Resistance isn't a real problem, just fit amplifiers or start with a higher voltage. Same reason that undersea power transmission is usually DC. Long cables are too lossy to AC.
Signal, reflections are also an issue, hence terminator resistors at both ends. Crazy complex science. Quite frankly, it's not good toilet-reading material at all.
Long cables are too lossy at AC? That was the problem Edison had with dc surely? Crank up the volts, reduce the current and I2R losses are smaller. At 50/60Hz L and C is a minor issue over long distances.
I believe that the reason cross country power cables are strung so high is to stop the extremely high voltages arcing to ground through items coming close enough to create a spark gap. There are numerous instances of wildfires being caused by hot transmission cables drooping close enough to the ground due to heat from the environment and current flow to start arcing to vegetation that has grown due to lack of maintenance around the line paths.
Unfortunately, in the last few years, here in N. California....people have died, small towns completely destroyed.....poorly trimmed trees arcing at the powerlines above. The cost in the end, 'Guilty' of 64 counts of manslaughter, huge $$ in fines....was much higher than just trimming the trees, and it's still occurring here, in N. California, USA.
I think the main misconception is that energy is transferred across wires in the first place. Even with the conventional theory, that does not hold since power is voltage times current and there is no voltage across a single wire. In the battery example, you can't point to a specific place where the energy is flowing since the current is flowing through the wires but the voltage is across the wires. But that doesn't prevent us from designing circuits, we can simply calculate how hot the wires become using current and if the isolation will hold using voltage. The pointing vector theory is certainly not disproved with any of the examples, but rather that it is just not practically applicable in everyday electronic design. Veratassium was plain wrong by his application to the ocean cable and he is very annoying by intentionally leaving out the fact that conventional theory simply follows from the Maxwell equations.
You can't have a current without a voltage difference in any wire that has resistance (and generally speaking, they all do). There is a voltage across a single wire if there is current flowing - it's just usually ignored when talking theory. Every wire dissipates power, and has voltage drop.
The Veritasium's video has some errors but the basic consept is what has been taught exactly like that for a long time already to (all?) electrical engineers. Nothing new there. EVVblog also has an easy to understand video about Veritasium's video: ruclips.net/video/VQsoG45Y_00/видео.html
@@tkermi True, but everybody seems to ignore the fact that we are all used to calculating power by multiplying the voltage and current (at the source or load, which can be the wire itself) but never ask ourselves what the exact path is that this power takes when designing circuits (including wiring circuits). I think this is mainly because it is irrelevant. Veratasium states that we are wrong about the way we thing about power flow, which everyone is reacting on, but I think we rarely thing about power flow in the first place. All we think about is current and voltage, and we only think about power when it is generated or dissipated. And yes, most (all?) electrical engineers think about the magnetic fields with relation to current and the electric field with relation to voltage, but again power is irrelevant most of the time.
This was an awesome video. I hope all these various RUclips responses get to him at some point so that he can do a video to address all the points that people brought up. He's certainly not completely wrong but there's nuance here I think that he would appreciate.
I think you need to bear in mind a couple of things: Theory in a scientific sense means 'we've tested this, a lot, and it makes the best sense of what we can see and allows us to make predictions', which is very unlike how the general public use theory ('I have a vague idea that might be right). An electron is just the name we give to a collection of characteristics that seems to behave in a certain way, and how we understand those characteristics has changed vastly over the last 100 years - as Dara O'Briain says, 'No, Science doesn't know everything, if it did, it would stop'.
The reduced load the battery sees at the moment the switch is thrown is Ibattery = Vbattery/(Rbulb + 2*Zo), because there's two lines attached in series with the bulb. They have a characteristic impedance (Zo) defined by geometry. In this case it's about 700 ohms per line. So the impedance of the lines will act as current limiting elements of about 1.4 kohms until about 1 second when the reflections begin to stabilize. Eventually the line impedances drop to zero and the battery only sees the bulb alone. It would basically look like 1) dim bulb as initial wave fronts propagate down the line sections (but YES occuring in 1/c seconds) 2) flickering with an approx 1Hz period, with bulb progressively brightening as reflections interact 3) bulb achieving full brightness as steady state is achieved
The point veritasium makes, is that Capacitance inductance Resistance and the other concepts we use in electrical enginering, are a semplification of what is really happening, which is the interaction of the fields with themselves, the wire and the surroundings. So you are kinda trying to explain why relativity is wrong, using newtonian gravity which is a semplified subset of the theory
But electrical engineering concepts are as wrong as Newtonian physics. It works for almost everything with incredible precision. No sane engineer will ever use Maxwell's equations for something that can be accurately described by the usual paradigm. They still learn them of course, because devices that work with fields need them. And even then, it's beneficial to simplify models from Maxwell's equations so it's possible to use them with the regular circuit paradigm.
As a lighting technician (for theater) I'm always shocked and excited when someone talks about my job. Can I ask, why you reached for that as an example? I mean, its understandable enough, especially how you describe it, but not exactly commonplace. And do you have more videos related to that topic? Also, you probably know this and didn't include it because it wasn't germane, but data cables for lighting networks use two lines for signal and a reference voltage cable which further helps to distinguish the signal from noise.
Make no mistake, Mr Veritassium knows much better than this. He even mixes fixed-state field equations with flow-based effects, which he has previously shown that he knows full well that you simply cannot do. I actually suspect he's just being as controversial as possible to get more fame - i.e more money. As we all know, truth is no longer something that matters. Only opinions and internet fame is important.
I would argue with you, but he used the word "lies" (or "lied" maybe) which seems so counter to his usual attitude, almost like he's trying to enter the market of the conspiracy nuts, anti-vaxers etc... he may as well have said the earth was flat. "Post-truth" is just historical revisionism. Post truth is the era where a chunk of people started to imagine that the past was different, and not simply that their exposure was different. Post truth is a sign of pre-ignorance, nothing more. Nothing "matters" objectively, "matters" is subjective, it has to matter TO something/someone. Objective truth does it exist, but it is foolish to believe you can know that you have it; the defining quality of being wrong is that it feels indistinguishable from being right.
I think veritasium oversimplified it too much but in some sense it is correct. However all circuits show a characteristic impedance which varies with the size of the wires and the distance between them. Now this characteristic impedance can be modeled as distributed capacitors and inductors and so it is easy to understand that there will be a current flowing in the circuit the instant the switch is turned on and if there is a lightbulb in that circuit it will receive a current. This current will be the voltage divided by the characteristic impedance. So if the voltage is 10V and the impedance is 100 ohm for instance the current would be 100mA. But when enough time has passed and the wave has traveled all the way to the end the wave sees the true impedance of the circuit and so the normal ohm's law applies. Note also that it will take double the time for the battery to see the true load because the wave has to travel all the way back from the load. It is basic wave theory but I hope it makes sense for anyone getting confused. In short it is oversimplified.
Stopped watching Veritasium a good time ago, seems like he's still into "quack-science" (take some pieces you like, ignore what doesn't suit you and come up with your own). Btw, protons, neutrons and electrons aren't the smallest building blocks - but when those things are explained by true scientists I tend to get a slight headache. (Sabine Hossenfelder and Sixty Symbols are two good channels in my opinion if someone wants a fact induced headache)
I don't think Vertiasium was wrong, but I think he presented the information in a purposefully ambiguous way. I think what he's describing is inductive coupling between the two sides of the circuit (because the length of the transmission line is so much longer than the distance between the ends). Therefore, when the switch is turned on, the wave front of voltage change heads along the cable at nearly the speed of light. This wave front is nominally square, so it has a lot of high frequency components to it. This high frequency energy will be transferred into the "return" portion of the line and, assuming your light is very efficient, it will light up. You won't be getting a lot of current, but you will see the current rise long before the wave front has had a chance to get out to half a light year and come back. In fact, the two lines don't even have to be connected, it just means you won't ever get the full current and the wave front will hit the open end of the cable and bounce back towards the source. There's probably some capacitive coupling going on as well, but I think the inductive part would be greater. Also, it's important to remember that he's talking about the transfer of _ENERGY_, not electricity. Electricity is carried in the wires, but the energy is carried in the fields surrounding the wires and that energy can be picked up and syphoned off by nearby wires.
I think we need a video of BC holding a fluorescent tube under HV lines to observe the effect :-)
At the tender age of 11, I held a fluorescent lamp in our front garden in 1973. The tube lit up as Clive described. In this case, it was quite bright. Why did it light up? Because my Dad was a radio ham. He had rigged up an aerial that went from the front garden wall, over the roof of the house, to the back garden. I'm not interested in ham radio, but I believe this aerial is called an inverted V. He then put quite a bit of RF power into this aerial, and hey presto, the tube lit up. Some poor chap that was driving past nearly crashed into a lamp post.
I'm pretty sure there are similar examples on Platonic Induction's channel
There is photos of People puttning dussins of them in the ground to make a spectial
At Glastonbury. In a line. with 100 other people to see how much light you can actually make... And the Guinness people there. Go for the World record of human-passively grounded fluorescent tiki lamps.
Been there done that on a dark night with a selection fluorescent tubes.
As a post office telephone apprentice I was taught two sets of knowledge in parallel. On day release at technical college I was taught electrical and electronic principles while in the workplace I was taught the PFM principle. As an intelligent individual with a pedantic nature and poor education I was fascinated with the formal electrical and electronic principles but soon realised that it’s a rabbit hole that gets deeper and more abstract the closer you look at it. In the workplace the PFM principal says this is Ohms law and this is Kershoffs law. Everything else that makes these things a fact is Pure Fucking Magic and trying to understand it will just confuse you.
Over the years, I’ve realised that trying to understand the root of these things is indeed confusing to the operational level of keeping most tech going. And given that since those early years I’ve managed projects where real live quantum physics have been employed by the very clever people to deliver a working system to a customer, I’ve learned that nodding in the right place and occasional grunts keeps,things moving.
Just to be clear from the outset, I am not an electrical or electronics engineer though I studied physics for far too many years of my life. I look at electrical theory like I look at gravity. At a practical level Newtonian dynamics and gravitational theory is good enough to get you to just about any place in the cosmos you want to go to. But Einstein's general theory of relativity is a better description of what's going on with gravity - its just really fecking difficult to apply at a practical level. Like you say electrical/electron theory is a black art still not fully nailed down even though we seem to have muddled through for over 200 years. Imagine what we will achieve when we really understand it
@@RaspberryWhy The burning question that's been in my mind is, are we just extremely skilled at manipulating this concept that we have a relatively loose grasp on the mechanical function of, or are we just barely scratching the surface of what it has to offer, limited by our relatively loose grasp on the mechanical function of? I feel like I'm relatively capable of making use of electricity with the fundamental knowledge that's taught today(mind you, self educated on the subject, not by any means an EE), but I can't help but wonder if there's just a "different level" of capability here that we're just a couple breakthroughs away from.
@@RyTrapp0 As a network specialist in the states, we had a phone issue yesterday, rebooted the Charter modem, problem solved. Though it did turn out to be a regional issue.
Both theories are correct, but the magnetic fields only really come into effect on signals and high frequencies.
Dave from EEVBlog made a good video on it a little back also as a response to Veritasium clickbait.
Praise the Omnissiah, and appease the Machine Spirits.
What is ingrained in my mind from a young age was when an electrician told me it was like "pushing marbles through a hose full of marbles. Add a marble in one end and one has to pop out the other end".
This is what I was taught, the electrons themselves flow slowly (we calculated it based on the equations in physics class) however its the 'propagation wave' of the analogy you give here that moves near the speed of light
Speed of light in the media(copper)
@@cimmerian100 True, but the point of the theory is that the energy itself doesn't even go through the wires. The current does, but the energy for the work done comes from the EM field.
Very simplistic. There would be a large propagation delay as the wave of electrons hopping between atoms at a tenth of a millimetre per second would take hours to reach the other end and pop out!
All the electrons move at once because the field propels them all at the speed of c. Engineers struggle with this concept because few of them are physicists and therefore have to unlearn a lot of simple stuff that enabled them to do their jobs, but is still an incomplete description of how the world really works. The Universe has no obligation to make sense!
A practical example is to recruit a friend who is both a smoker and tuba player. With a lungful of cancer-stuff have him play his favorite ditty. Wait until you can see smoke coming out of the bell--it will be a considerable time after you hear the sound.
Clive: "Say this an electrical distribution tower..."
* draws two giant scowling penguins *
Me: "...wait."
Also, I'm pretty sure those penguins are in the KKK.
lol 😆
It's the baddie from "The Wrong Trousers" :D
🤣🤣
It looks like little Dwight drew his dad Daryl and his uncle Hoyt holding a length of rope.
Veritasium clearly wanted to explain the physics of electromagnetism, in particular the Poynting vector and the concept of the electromagnetic field (which is a different thing to "electromagnetic fields" by the way), and in so doing tried to come up with a simple thought experiment that would show how counterintuitive the theory is for the average person. To make it work, he assumes the wires are superconducting, that the switch and battery are ideal and that the lamp will come on with any current above zero, even infinitesimally small. He also assumes the usual things about the experiment being completely isolated from interference from the rest of the world.
The problem is that he leaves the viewer with the impression that energy flows from the battery to the lamp *primarily* through the 1m gap, rather than "along" the wires. To justify this he does a bait and switch. He shows a small electrical circuit with a lamp and a switch in which the Poynting vector is somewhat correctly drawn traveling more or less across from the battery to the lamp (in fact a vector has a magnitude and direction, it is not a continuous curve from one location to another). He then switches back to his lightsecond setup and implies that the Poynting vector points directly across from his battery to the lamp in that setup too and so implies that most of the energy is transmitted from the battery directly across to the lamp at the speed of light.
There are many problems here. Firstly, in his setup, the potential difference initially exists across the switch, assuming his lightsecond long cables took more than a couple of seconds for him to set up. This means that the disturbance which causes current to flow, and resulting electromagnetic fields, propagates from the switch, not the battery.
Second, in his setup, the Poynting vector is zero at the surface of the wires because they are superconductors (in electrostatics, for wires with nonzero resistance the Poynting vector usually points into the wires in DC conditions due to ohmic heating, i.e. the energy is flowing *into* the wires to heat them; but that is not the case in Derek's superconducting setup). But external to superconducting wires the Poynting vector is *along* the wires, parallel to them, but with rapidly decreasing magnitude as you move further from the wires. In other words *MOST* of the energy flux is along and very close to the wires, in the electromagnetic field, which much more easily aligns with intuition than Derek's extremely misleading video.
Thirdly, Derek very strongly hinted that his claim could be experimentally verified, which is bollucks. Even if he just uses lines of a kilometer instead of a light second, he won't find a lamp that will turn on with infinitesimal current. He won't find a kilometer of cheap superconducting wire either. The reality is the globe will light after about 1s as the bulk of the energy is concentrated very close to the wires.
However, having said all that, there is a transient that propagates from the switch along the wires that induces a tiny (negligible) current in the wire 1m away due to coupling through the electromagnetic field. If the light could turn on with infinitesimal current it would light after just a few nanoseconds. In this specific time there is a very small amount of energy *radiated* from one side to the lamp on the other side at the speed of light. It's not steady state and will fluctuate due to capacitive and inductive effects and signal bouncing around and so on. But technically it is there. It just has nothing whatsoever to do with how the potential energy in the vicinity of superconducting wires is distributed in the large.
The fundamental point that individual electrons do not have to move all the way around the circuit to the lamp for it to light is however correct. The *average* speed of the electrons is in fact very slow, orders of magnitude slower than propagation of energy in the electromagnetic field. The energy is in fact transmitted through the electromagnetic field in the direction of the Poynting vector, but for all intents and purposes this happens to be parallel to the wires mostly just outside the wires in the steady state.
The whole thing is complicated by the fact that as phrased, the problem is an electrodynamics problem and not an electrostatics problem. Thus many of the usual equations people want to apply simply aren't valid until the system reaches steady state. It's also complicated by causality. For example you can't think of the wires as a giant capacitor because in 3ns only 1m of the wire either side of the switch is even relevant to consider due to causality (finite speed of light).
By the way, there are some fascinating experiments that have been done to measure the electromagnetic field just outside an ordinary resistive wire using tiny seeds. In the vicinity of the wires the Poynting vector really doesn't point away from the battery towards the lamp when a DC current flows, but mostly along and slightly towards the wires. However, at the lamp, due to the fact that it is a resistive element, the Poynting vector points mostly towards the lamp. Energy comes out of the region surrounding the lamp because a potential is established there due to the wires carrying it there. This potential establishes a current (flow of electrons) in the lamp, and the potential energy in the vicinity of the lamp due to the potential established by the wires is converted to light and heat in the lamp. In the DC case *zero* energy is radiated from the battery, and I really mean zero, not approximately zero. Instead, the Poynting vector at the lamp shows the energy flux from potential energy in the region about the lamp into the lamp where it is converted to light and heat energy. I've tried pointing this out to the nerds who claim otherwise but years on they still insist they are right.
Even with all these magic tricks, his answer is still wrong, because just closing the switch does not cause instantaneous step-like change in EM field that can be picked right after 1/c seconds. This is not what happens when you close the switch. EM fields can only change when sufficient amount of electrons had time to change their positions and average velocity.
He wanted a controversial video. He's a self promoter first, RUclipsr second, then a science popularizer.
@goodwillhart I agree with just about everything you say, but I have one small quibble: you state: "But external to superconducting wires the Poynting vector is along the wires, parallel to them, but with rapidly decreasing magnitude as you move further from the wires." That's pretty much untrue. The Poynting vector has a magnitude and a direction, but has nothing to do with the orientation of the wires.
If you have a battery, two wires and a bulb like in Clive's diagram, it doesn't matter if the top wire goes up, then right, then down to the bulb. The electric field will have a direction from the top wire to the bottom wire, while the magnetic field will be around the wire. If you consider a cylinder surrounding any part of the wire, then calculate the Poynting vector for the flux into one end of the cylinder, it will be equal to the Poynting vector for the flux coming out of the other end of the cylinder, and it will always point from left to right, i.e. from battery to bulb, regardless of which way the wire is pointing.
If you change the orientation of any part of the wire, you change the direction of the electric field between it and the other wire in such a way that the Poynting vector will remain in the same left-to-right direction. It has to because the Poynting vector is just a way of calculating flow of electrical energy, and electrical energy is either conserved or transformed into an equivalent amount of another form of energy (such as in the bulb).
@@tbird-z1r ...and thus, the Veritasium video is more like confusing psycho-babble than anything enlightening, whatever level at which viewers appreciate electrical theories. He should take the video down and re-make it with more scientific rigour - this is the first time he's really disappointed me.
Veritasium clearly wanted to generate controversy and clicks, and thus revenue. Mission accomplished. His goal was not to increase understanding, because he did exactly the opposite.
In the original Transatlantic cable, they didn't use sounders but instead used very sensitive galvanometers. It took on the order of ten seconds to transition from a dot to a space. The throughput rate was very slow. As the cable began to fail, they kept stepping up the voltage until the cable completely failed. They had to wait until after the American Civil war to run a new cable.
Two ships carried the entire assembled length of cable (tested in harbor before the ships ever left) They then sailed to the half way point and began laying the cable in opposite directions until they reached both shores.
Yes this is exactly as I heard it too. They basically screwed it up in short order.
Ohm My Gauss! 10sec?! The patience of the operators: godlike.
right, it worked initially...
That slow change was probably a capacitive effect, the very long run of two conductors separated by a dielectric material acted like one ginormous capacitor. So when they closed the circuit, power would flow in but had to slowly charge that huge capacitor before any noticeable voltage increase would be seen at the other end.
What's the American Civil War got to do with it? The cables ran England - Ireland - Newfoundland and were designed, built and layed by British companies. As more cables were layed, increasing amounts of American investment money were needed. Is that what you're suggesting? The second cable was delayed because of a lack of US investment, caused by the war? That's not in my history books. Or is this another 'America built, discovered and invented everything' sort of theme?
Early telegraph systems used a single open wire and earth return over significant distances and worked just fine. The problem occurred when these wires were laid underground or under the ocean. The additional capacitance of the cable, coupled with its resistance, caused the rise and fall times of the current to be unacceptably long. When the first transatlantic telegraph cable showed this effect the reaction of the chief engineer was to increase the applied voltage. Unfortunately the increased voltage was too much for the insulation which broke down, and it didn't even cure the problem. It was the invention of "loading", which deliberately increased the inductance of the cable which, somewhat counter-intuitively, solved the problem. I can't remember off the top of my head which scientist it was that came up with that, but it was employed on later transatlantic telegraph cables. The technique was also used on telephone circuits until quite recently. When digital transmission (PCM) replaced audio on some medium-distance circuits in the 1960s and 70s the loading coils were replaced by digital regenerators.
Oliver Heaviside is who you're thinking of.
May I address the Elephant in the room...?
Is your last name *actually* Faraday? :P
@@DUKE_of_RAMBLE Sadly not. I stole the name for my YT presence as my real surname name is unusual making it too easy for someone to identify me. But I am a retired telecomms engineer with a strong interest in the history of the industry.
As far as I know the output end of the early long-distance cables was not a sounder but an optical galvanometer. This is a typical electrical meter with a coil in a magnetic field, but the coil is very delicately balanced and has a fragment of mirror mounted on it. A light beam reflects off the mirror and illuminates a scale. The light beam takes the place of the needle in a regular meter. The advantage is that as the light beam has no mass it can be made arbitrarily long to amplify any movement in the mirror.
That was put on after the cable did not work because the signal was too weak. It saved the day and all the money invested and they use the cable to send messages.
A mirror galvanometer.
@@SynKronos perhaps, but the significance is that there isn't the momentum which would impact the amplified signal. Consider a hypothetical device which was moving a long metal arm. Short movements at the pivot would be amplified into observable large movements, but changing direction of the arm would not be instantaneous and would have to counter the momentum in that arm. There's still a moment in moving the mirror at the pivot, but the arm is now replaced with a beam of light. That beam doesn't have a moment, so the change in direction is only affected by the moment of the mirror, so the amplification can just be extended by extending the range that the beam is cast.
Originally, it was not a mirror galvanometer. They had to bring in Lord Kelvin who added the mirror galvanometers as a way to solve the many problems that BigClive so nicely described. Veritasium's analysis treats batteries like the sun. The sun clearly sends energy, this power, to the earth through the vacuum of space. Batteries do not work that way, or else you could just show the battery to a light bulb and it would light up. "In theory, practice and theory are the same. In practice, they're not." - Yogi Berra
@@SynKronos If you are referring to the light beam, it has momentum rather than mass, doesn't it? If you could somehow isolate and "weigh" a photon, I seem to recall it would be massless, though is does have energy that could be measured as mass due to the mass-energy equivalence.
There would (theoretically) be some microscopic displacement of the mirror due to the impact and reflection of the incident beam, but (at a guess) it would be insignificant, even in this experiment.
(Note that my uni physics was near 40 years ago, so some of this physics is a bit dusty up there in the ol' attic. Feel free to refresh it!)
At 5:45 "The formulas being applied to justify saying the current flows on the outside; I get the feeling that they largely apply to the radio part of the spectrum". No Clive.
The claim is that the _energy_ is flowing outside of the wire. Nobody is saying that the current in the circuit you drew is flowing anywhere except inside the wire.
But the wire connecting the battery positive to the bulb (call it the red wire) will be at battery voltage (say +1.5V) and the wire connecting the bulb to the battery negative (call it the black wire) will be at 0V. That means a voltage exists between all of the red wire and all of the black wire that gives rise to a static electric field that we call E between the wires which is the change in volts per metre from the red wire to the black wire.
There is also a static magnetic field going around the wire which is associated with the steady current flowing through the wire.
Someone called Poynting realised that when we have an electric field (in your diagram from the top wire to the bottom wire) that crosses perpendicular to a magnetic field (in your diagram going into or out of the paper) then you could calculate what is called the vector product ( *E x H* ) and it would be a vector with a magnitude equal to the energy flow and a direction perpendicular to both E and H (in your diagram, from left to right, i.e. battery to bulb).
In other words, there is a way of looking at the static electric and magnetic fields that occur in a DC circuit like your diagram and deriving the power delivered from the battery to the bulb. It comes out to be exactly equal in size to the conventional volts times amps that we normally use. In that sense, we can say that the electrical energy flows via the static electric and magnetic fields that exist outside of wires that have current flowing through them, and calculate *E x H* . But we could also say that the energy flows with the current and calculate V times I. It's just two ways of looking at the same thing, and the result is necessarily the same.
You'll note, therefore, that I've emphasised the static nature of the fields and the steady current. There's no electromagnetic radiation of any frequency involved, nor any waves, and certainly not "the radio part of the spectrum". That's for your circuit drawn around the 5 minute mark, and I though you might appreciate a clarification of what is actually going on in that simple circuit.
Nevertheless, as soon as you get switches closing and both voltages and currents changing, you're in another ballgame. In that case, there are transient electromagnetic waves radiating through the air which can also carry energy (although not much in comparison to the energy associated with the current flow in the steady case). It was the ability of the original presenter to conflate these two different phenomena that has led to all the debate.
Sanity check: Run your wires through a faraday cage with a 3mm cable penetration. Heck, make it an S-bend. Does the bulb illuminate? Well maybe the situation here is more complicated than we had hoped. Edit: For a bonus put a smaller mumetal cage around the bulb to make sure the H field is also completely dealt with.... still illuminating? Damn.... electricity doesn't care about our Poynting Vector derivations.
Big bwain
And the Pointing vector derivation doesn't care about your electricity. The faraday cage doesn't "turn off" fields, it simply confines the field (that we care about) to the 3mm cable penetration. For DC this difference is immeasurably small, as they are mostly there already, but for signals in the radio frequency spectrum the difference may be significant. Fields are always conserved. Think about a simple electron in empty space, and the electric flux it creates which is always proportional to its charge, no matter at what distance you measure it (over the whole sphere!). Now place a metal sphere next to the electron. Locally the field is changed, but as the metal is neutrally charged, the overall charge is not changed and the flux is the same. Now put the sphere around the electron. Does the field go away? No! Metals are just (in this case neutralized) masses of movable electrons. They will be repelled from our original electron, so the inner surface gets positively charged and the outside negatively, creating a dipole field with the exact same global flux outward as the initial electron had. Analogous rules apply for currents and magnetic fields. Fields are ALWAYS conserved. If you do the pointing derivation for energy transfer, it matches perfectly with the real world. In DC circumstances the energy is confined to the conductors. In high frequency situations the whole circuit becomes (to simplify) an amalgamation of capacitors, most of the energy follows the path of least impedance, some will go straight through the air. It is counterintuitive. Like relativity. Doesn't change the fact that it's reality. And yes, Veritasium's image is misleading as it shows lots of the energy fields going outside the circuit in a DC condition, which is wrong.
@@naturallyinterested7569 how do you save a comment?
@@roxasparks what do you mean?
@@naturallyinterested7569 i liked your funny words magic man... i screen capped em!! 😏
Veritasium also selectively left out variables and misrepresented the case...
And it's nice to have your take on it!
He ignored I2R losses that made me suspicious instantly.
He has a tendency to do that, he did a video on self driving cars a while back, titled something like 'why you should want driverless cars now' and how they have the experience of millions of drivers and conveniently left out the fact that all that experience was of the same 5 mile stretch of road. The thing hilariously does an emergency break when someone walks past on the pavement, if it wasn't a controlled car park it would have been a dangerous manoeuvre and he tries to play it off as if it was a good thing, and all I could think was how bad were all the other takes if you were filming all day and you left in the shot that nearly gave you whiplash and how much did they pay you for the sponsorship?
Infotainment needs to be taken with a pinch of salt. Popular RUclipsrs always prioritize making a video over making it worth anything. Of course, everyone loves to feel like they are educated after just watching a video, so sycophancy kicks in. If one really cared about learning physics, there are plenty of lectures from reputable experts out there, but there are fewer bright colors and jumps cuts.
@@YearRoundHibernater What's worrying to me is that, him having spoken about this publicly before, he's starting to stray past his original goal with the channel which was to "Create educational videos that would blow PBS out of the water" rather than clickbait and semi-researched videos. I know a semi-popular youtube creator and I've seen the huge struggles behind the scenes where even with good intentions you can create clickbait and the only things you can react to are the hate comments that seemingly come no matter what you make. It makes it very, very challenging to get good criticism on things unless you have a specific group of viewers who can give you feedback (Patreon discords can be a great example of this) or have a third party review videos before they can come out (which has a whole host of other terrible problems). I had to stop watching veritasium once it started getting into stuff I've personally experienced or know someone who is an expert in those fields and it turned me off of the entire channel. I know his intnetions are genuinely awesome, and the hard work he's done to make it happen SHOULD be praised, but the last 5 videos have just felt extremely underwhelming and very one-sided compared to videos in the past. People have given much better criticism than I ever could on this in the comments of each of those videos but I don't really know if there's a good way to communicate that.
The best thing about the veritasium video is seeing all of these videos discussing the subject. I certainly have learned more from all the discussions happening in videos.
He does know how to stimulate discussion.
After watching the many videos about Vertasium's video. First of all my head is exploding. Second I think he was on about the speed of electron flow as the electrons only move slowly through the conductors as opposed to the fact the light in the bulb is quite instantaneous. In another video, they described the flow as different in the centre than towards the edge of the conductor. My brain is still exploding.
@@atlanticx100 It really shouldn't be exploding. He is very misleading cause his version of the light bulb "turning on" is just induction in the wires causing the light bulb to turn on for a brief amount of time, and since its DC electricity this induction goes away as fast as it was first generated.
@@atlanticx100 Think of it the same way as pushing a stick. The other end of the stick responds pretty quickly, at the speed of sound, in the order of 1000m/s depending on what material the stick is made of, while the actual atoms in the stick would be moving at maybe 2mm/s.
@@bigclivedotcom What bothers me most about the Veritasium's video is that it's almost a copy of a The Science Asylum's video from 2019, I have no idea how original that is by te way;
ruclips.net/video/C7tQJ42nGno/видео.html
Basically, Veritasium’s explanation is just a difference in semantics. He drew the fields outside the wire and said the power is in the fields, not the wire. But those fields are created by electrons moving in the wire, and so the wire is still necessary!
It’s possible to transmit power wirelessly, but it’s inefficient at a distance. We do it all the time with radio.
benjamin brooks, as you wisely say, that the fields wont exist without the electrons moving in the wire is a very good point.
What he said was that the energy was transfeared by the electromagnetic fields around the wires not by the electrons in the wire. What I didn't think about watching veritasums video is the connection to photons! Accelerating electrons will produce photons not electrons with constant motion.... Don't know where I am going with it. Can an electromagnetic field propagate energy without photons?
@@lubricustheslippery5028 a photon is the smallest discrete measurement of an electromagnetic field. You can get it to behave like a particle (double slit experiment) but it is in fact the electromagnetic radiation. So to answer your question, no, by definition! If you have EM radiation, we call it’s smallest possible state a photon.
His assertion about the super long cables with switch and light next to each other is completely wrong, though. I'm speaking from a practical point of view - a smaller scale version of that experiment is performed all the time to measure the electrical length of RF cable used in phased array RADARs. For a given type of cable, the physical location of the ends of the cables does not make any difference to the propagation delay, only the length of the cable.
I'm curious about why - if the power is in the fields and not the wire - does the wire get hotter as more current passes along it? That seems to indicate there's something power-related going on in the wire itself. And for that matter, what's happening at the lamp itself where all this power is being used? If it's an incandescant lamp - which is just another sort of wire - is all the power suddenly switching from being "in the fields" to being "in the wire" in order to make it glow?
I have used a Time Domain Refectometer for years and the thought that cable length and its distributed impendences are not important to electrical flow in a conductor, is, well idiotic and an insult to Charles-Augustin de Coulomb.
One of the most underated test instruments ever. TDRs can perform magic. Or at least it seems that way. 👍🏻
Luckily Derek's mental exercise contains all manner of practically implausible assumptions, so it would be a little foreign to expect a practically plausible result.
Without 'repeaters' every so often to reform any pulse wave shape, the inductance and capacitance of the cable will 'reshape' the square wave of a morse code signal into something similar to a sine wave. The overall metal jacket will look like a shorted turn to the signal further degrade the signal. I shook my head when I read 'Vs' description but there were already too many comments. Thank you for challenging his missive.
@T.J. Kong "An infinite series of sine waves" isn't exactly a *physical* explanation - it's a mathematical treatment.
Not repeaters. Heaviside should have made millions when he invented his Telegrapher's Equation. Hang just the right inductors and or capacitors all along your DC telegraph cable, and dispersion is set to zero. This also removed the barrier from phone lines (which were distorted and useless if longer than about 50 miles.) But Bell Tel screwed Heaviside out of his invention of long-distance telephone, instead promoting their own golden boy, M.I. Pupin, who simply lifted Heaviside's invention; taking false acclaim as if he'd invented it.
The capacitance of microphone cable on the cheap stuff can be heard by picking up the cable in the middle and dropping it on the floor. An audible sound can be heard.
"An audible sound can be heard." is kind of a double (triple?) tautology. :-P
I want to watch BigClive and ElectroBOOM eat a very large pizza together
4:45 What I've once read, was that Maxwell began doing calculations on some phenomenon, and then his calculations showed that that phenomenon actually propagated at a *very* particular speed, c, the same speed as light. So he concluded that the phenomenon, electrical fields or magnetic fields or something, was somehow a kind of light, or was similar to light.
It's almost three decades since I read that in a popular science book, though, and I've never really been able to understand advanced physics because calculus is a mystery to me.
Maxwell built on the work of Faraday and Weber: watch?v=DlMufPAtf4M
Maxwell did unit analisys of the permeability of a vacuum (4*PI*10^-7*Hm^-1 = (kg * m^1 * s^-2 * A^-2) ) multiplied by the permittivity constant (8.854*10^-12*Fm^-1 = (A^2 * s^4 *kg^-1 * m^-3) ). So the kg, and A components cancel out, and you are left with (m^-2 * s^2) . He noticed that the units left remaining gave a speed, and when he calculated that speed he noticed that it was very close to the estimate for the speed of light! i.e. c = SQRT(1/(4Pi*10^-7 * 8.854*10^-12) ) = 299795637.7 ms^-1
My problem too, Peter. Despite the intervention of many, anything but the simplest maths was a complete blind spot for me. I would have loved to be an electrical engineer - well, any sort of engineer, really. I had to content myself with studying a biomedical degree.
@@johndoggett808 I doubt he reached his result by doing unit analysis on the famous equations that was his result and on the SI system derived from his results.
@@johndododoe1411 He was doing unit analysis on two constants, not on equations. Obviously he wasn't using SI units, but a length is a length, and a second is a second. It was when the speed of light popped out, that he realised the connection between light and electromagnetism.
A curious tidbit about the 'arrow' on diodes and transistors. It's representative of a point contact diode. The line across the end of the arrow represents the germanium crystal and the arrow represents the cat's whisker. It doesn't have anything to do with current flow. It's just a happy coincidence it matches conventional current. The same symbol was used for point contact transistors. The base is a germanium crystal and the two diagonal lines coming off it are the collector and emitter, where the emitter was the one with the arrow head. That's a PNP transistor, as all point contact transistors are, and the arrow was simply flipped for NPN transistors.
Way back when I was taking this in school, we had this mnemonic to remember which transistor was which: NPN = Never Points (i)N.
@@jamesbrown4092 And for PNP we used, "Points iN Positively" :)
@@mikefochtman7164 Hey, I like that.
Something I was told by a dead Imperial College physicist: "Optical is really a tiny part of the spectrum. It just happens to coincide with the tight band of radiation that matter (solid stuff) reflects". The fact we can see "light" is no accident.
Proof that God exists.
@@bitterlemonboy Which God? There are so many of them now, I've lost count!
"Optical" is actually a very narrow part of the EM spectrum that coincides with the the peak frequencies emitted by the sun that reach the Earth. It's hardly surprising that animals evolved with eyes that can respond to (i.e. see) what is the strongest EM stimulation commonly available to them. Matter, solid or otherwise, reflects a vast range of different frequencies of EM radiation, as radio hams are very aware.
@@ahaveland The one that isn't made up.
@@ahaveland The one true God
I’ve been teaching atomic structure for longer than I’d like to admit. I liken our understanding of it to casting shadows. In the case of the electron, we can determine the mass of a single one very precisely, but we can’t know it’s exact location. We can count the number of electrons that move when a current is passed, but, as you point out, we have no way of knowing how that current actually moves through a conductor. It’s important to approach new theories with an open mind, but also to apply the logic we’ve learned to them. Keeping a civil and informed discussion going is worthwhile.
Dave at EEVblog actually explained this one for me (odd cause I usually fall asleep before he gets to his point). I twigged that Veritasium he was talking about signals while ostensibly suggesting it was about power when he brought up transatlantic cables, but his answer violating the speed of light (and the unit/dimension problem) made no sense to me till Dave pointed out that he has his loop was 1m from side to side and that was part of the thought experiment and not just a constraint of trying to get a prop in frame. The original video was talking about free space signal propagation, and not about power delivery (the zero resistance wire is a red herring, but the infinitely fast turning on bulb with any potential at all was very well glossed over). Frankly I would watch a video about radio any day of the week, selling it as being about power delivery is just fraudulent.
Also VT states the light will almost instantly turn on "to some extent"...
Which probably is not that much at all
From what I understand the most misleading part of the VT setup is that the "immediate wireless effect" of the battery on the light bulb will probably be the same even if they are on different circuits not connected to each other at all. So what's the point of presenting it like that?
Even with the magical lamps that is "turned on" by any voltage¤t(why it isn't always on then?), zero-resistance wire(but it still has electrons carrying charges and they continue to behave like electrons, and it has capacitance and inductivity?), with infinitely small and infinitely fast and otherwise perfect switch, Veritasium's "1/c" answer is still wrong. Because at the moment of closing the switch no instanteneous change in EM field is created, that can be received at 1 meter after 1/c seconds. This is not how switches work, this is not how antennas work. You need non-zero time for charge to re-distribute by traveling along the wire around the switch and *only then* there is a change in electric potential and current that will cause a change in EM field that can be picked up by the opposite side over the air gap.
Dave made a very bad simulation, actually. I recommend watching videos from "Z Y" channel, he presents some proper simulations and comes to the same conclusion as the experts Ve has consulted.
@@victortitov1740 This video disproves "Z A" claims ruclips.net/video/-jJB8dyOJIw/видео.html mathematically and logically.
I've worked in the telecommunications industry and have seen some amazing faults related to several aspects you have mentioned. Most commonly on analogue lines galvanic damage due to rain water. But I've also seen a sympathetic signal resonance between a taxi cab radio dispatch and a telephone line to a bookmakers. That was fun.
What made Veritasium's Video so frustrating is the lack of an explanation of his assumptions - and the implications of these. For example, his "light bulb" is a device which cannot exist - it is able to turn on for any infinitesimally small current, yet it does not get turned on by the leakage current of the air.
Can’t stand the bloke, his infinite hotel room one is also bollocks
I think VT's biggest problem is not making the distinction between "a signal" and "a flow". A signal is seen at the light bulb almost instantly because of induction between the wires, and that signal itself induces a flow, in reverse to the flow that would eventually come when the actual electrical flow picks up. Better, when the flow _does_ catch up, a lot of it will have been interfered with by the reverse flow transmitting wirelessly as a signal between the wires through induction. The undersea cables are related because, as Clive was getting to, nature is _full_ of tiny magnetic and electrical fields and potentials, so trying to pass a stable one through all that will see signal interference from millions of chaotic sources, which don't do much individually but add up over hundreds or thousands of miles.
He treated "flow" and "field" as mutually exclusive, when "field" is actually the mathematical description of the forces exerted by particles (E-field) and their flow (B-field). It's like saying that mass is released as energy, BECAUSE of the equals sign in Einstein's famous equation, or that time flows one way BECAUSE of entropy. A description of something is not a force, it has no cause or effect.
I'm not knowledgeable on this stuff, but don't you need AC for induction to happen? I thought that for that reason transformers only apply to AC. My understanding is that a DC current will cause an electromagnetic field, but it's not a _changing_ field so it won't induce a current in the other wire.
@@captainchaos3667.. ok , it's been a long time , so I hope I get this right .. keeping it simple .. think DC solenoid / relay etc .. the DC current "induces" a magnetic field , and makes stuff do stuff ... solenoid is probably easiest to imagine
@@captainchaos3667 you need changing magnetic field to induce current. If everything is stationary then you need AC for that. But you can wrap some wire under DC around a core, and move that core around. That's actually how generators work.
I don't quite understand what you mean by "signal is seen at the light bulb almost instantly because of induction between the wires". Signal is seen, induction definitely happens, but why is that an explanation?
I’m here simply b/c of the phrase “naughty Mr. Veritasium”
"an electric shock is a very special thing too"
I would argue that the last electric shock that almost killed me was quite terrifying.
Last weekend I vaccumed my room and got shocked when I touched the metal tube. The arc was about 1.5cm long and hurt like hell. Can confirm they are "special".
@@mathewcherrystone9479 I've bought two cotton tracksuits and let me tell you they love the fluffy polyester blanket on my couch. I've never been that charged in my life, not only does every door handle bite me like it's defending its young, but I also have fried a set of fairy lights by touching it and yes the arcs I create are quite impressive 😂
@@birdgirl8390 This sounds like the worst super power ever.😅
Take it from me, it's a very special kind of shock that you get from a 12kV flyback transformer. Those things leave a burn mark on entry and exit.
So thankful you addressed this. In a way you describe his thought better than he did (for my brain). I love when 'in theory' goes against 'in practice'.
I thought Veritasium did a horrible job explaining this theory.
@@Varangian_af_Scaniae its like he intentionally explained it badly to make it click bait
@@matsv201 I don't think that click bait and the content (in that case the quality of Veritasium's explanation) have to be related. If they were, it wouldn't be click bait.
In that case, I think Veritasium actually tried to make a clear explanation about how energy is transported, but simply did a job so bad, it caused confusion instead.
@@oilybrakes it wasnt. Not only was it a poor explination, it was also not accurate.
He bloody well knew he was leaving out bits of known information!
My first reaction to veritasium's video was "if its the fields carrying the power, why do you need the cable?" His whole explanation with the chain and mentioning how our electrical system has breaks in it really rubbed me the wrong way. the electron drift in one wire induces the drift in an adjacent wire either through inductance or capacitance. In between these breaks, energy is transferred from one side to the other via electric and magnetic fields. But inside the wire it really is that electron drift carrying the energy. The whole reason an incandescent lightbulb glows to begin with is because the electrons drifting through the filament have a sort of electromagnetic "friction" with the stationary nuclei that produces heat, which in turn produces black body radiation. Placing a lightbulb in a strong electromagnetic field without allowing the electrons to drift would not illuminate the bulb.
It's fact that energy is contained within the field, not the wire. The issue with Veritasium's video is the conclusions he draws from that fact.
@@Dukey8668 Can you fundamentally make a difference between whether the energy is contained in the field or the wire? If one does not just exist without the other. They're potentially just two ways of looking at the same thing. Like of course charge spans a field that causes a measurable physical interaction at a distance, but whether the field "contains" that energy seems like an entirely pointless squabble.
@@SianaGearz " Can you fundamentally make a difference between whether the energy is contained in the field or the wire?" Is the energy in a garden hose in the water or the hose? Without the hose the water just falls to the ground, the hose merely contains the energy that the water has. This is probably a fairly apt analogy for EM fields and wire.
@@SianaGearz It has massive relevancy to PCB design. Watch some of Rick Hartley's lectures - he can do a far better job explaining it than can I.
@@Dukey8668 so what? The field does describe the interaction that happens at a distance, this is the whole purpose of this construct. It doesn't say anything about where the energy is "contained".
In fact we don't know how the nature works, physics as a whole is a predictive model based on conventions and constructs that appear useful, they don't have an ambition of being true in the fundamental sense. These constructs are functionally true because their predictive power is proven experimentally, they are not fundamentally true, in fact fundamental nature of most phenomena is likely unknowable. And science popularisers like Derek I feel are doing the world a disservice by presenting these models as the fundamental or absolute truth.
Part of the reason buried cables power cables aren't as affected by capacitance to the earth is that the phases are balanced. If you observe a section of cable from the outside the total charge inside is always the same.
5:20 Nitpickers’ corner: between Microwave and IR, there’s a range of frequencies up in the low-mid terahertz range that we hadn’t really figured out what to do with for the longest time. The last I’d read about it (about 8 years ago I’d say), the prevailing research was on using it for backscatter scanning, in airport security and possibly medical imaging applications.
Hoping someone will chime in with any current knowledge on this.
The problem is none of our modern methods of making electronic components will work above about 1 Terahertz. So electronic circuits don't work there. Below long IR, optical technologies really don't work. So there's a small no-mans-land in between radio and optical that our technology currently can't exploit. If we could make electronic components like diodes that would work at optical frequencies, we could make nearly 100% efficient solar panels with bazillions of optical diodes and wavelength sized dipole antennas. But we can't, so we're stuck with the photoelectric effect that only allows about 30% efficiency.
@@stargazer7644 plasmon resonance works in the TeraHertz range quite well. But you have to build your antennas from atoms. (see: pentacene, graphene)
@@adamrak7560 What does plasmon resonance have to do with practical electronic circuits? Can you use it to make a radio that operates above one terahertz?
@@stargazer7644 Well that field is actually called plasmonics, and yes it can dovetail with modern electronics. Given your name I assume you know submillimeter observatories also exist under the umbrella of radio astronomy. Historically people have had to use special vacuum tubes like travelling wave tubes and klystrons to amplify such signals but apparently there are actually transistors (HEMT's) that can now provide gain in that regime. Needless to say it's a field of active research. en.wikipedia.org/wiki/High-electron-mobility_transistor
@@whatelseison8970 Wow!!!! That’s really cool, that article also explains how GaN-based power transistors are so efficient compared to their silicon equivalents, something I hadn’t really read about before outside of speculative press releases.
I think it's pretty amazing people invented all these different types of components when our understanding of how energy moves isn't so clear and potentially was wrong. Like when the diode was invented the inventor was using a model where electrons were moving from positive to negative.
Apparently not, from a comment above, the first diodes were vacuum tubes, where knowledge of electron flow was just fine (and pretty much required I would think). The electrons spread out as they head towards the positive plate.
This is why I've always felt that you do not have to be a complete expert to fix/build/make something...especially with access to the internet. So many of the major inventions we use every day, were not understood when they were invented! Even youtube was meant to be a dating website...here we are talking electrical theory!
@@ryanroberts1104 YT dating site? Are you thinking of Face(Stalker)book?
@@hayuseen6683 No, it's every bit as clear as I said it, youtube was started as a dating service. It failed.
@@ryanroberts1104 ah, pre-google youtube. Interesting. I guess most social media is powered by boners, in the end.
The symbol for a diode comes from the old vacuum tube, where the electrons of the filament are being emitted towards the plate. The triangle is the cloud of electrons spreading out from the filament towards the plate.
So it is electron flow after all!
@@crackedemerald4930 I wondered how the Veritasium theory fitted with valves, CRTs etc. These (esp CRTs) operate with high velocity beams of electrons flowing in a vacuum, or at least that's what I was taught.
@@davidfaraday7963 it's strange how People are calling it *his* theory. But i guess it's easier than "pointing vector theory as presented by veritasium"
@@crackedemerald4930 Right -- except it's Poynting... definitely autocorrect-bait :-)
@@Graham_Wideman the letter y is one of the worst letters in the english language
I have seen all video responses to veritasium and BC is the one that gives a simple and understable explanation.
Nick over at The Science Asylum did a video on this about 3 years ago, without all of the distractions that Veritasium added: ruclips.net/video/C7tQJ42nGno/видео.html . His video includes a nice time-line, beginning with Ben Franklin losing the coin-flip about which charge actually carries current in wires, jumps ahead to Joseph John Tomson's discovery (1897) of the electron (in cathode ray tubes) and back to John Henry Poynting's theory of energy flow (1884, so not exactly "new", and not dependent on electron theory at all, since the electron hadn't even been "discovered" yet). While this theory is counter-intuitive overkill for understanding (low frequency) power flow through wires, if it wasn't true in all cases, there would be no such thing as radio.
Yeah, I keep trying to get people to go look at that one. The implications are far, far more important than any of the examples Derek used. This one quote: "According to Poynting, energy _cannot_ flow in the same direction as the charge." It's a vastly more powerful claim, and proven, as you said.
Nicks channel is really good and I love his teaching style. Well worth looking at.
@@oasntet But is that because Electrons are negatively charged ? ( and have low denstity/mass). What happened to the Positron - is that Antimatter related ?
I keep thinking about this. I feel like Veritasiam watched the science asylum video and didn't totally understand it...
@@highpath4776 I'm not 100% certain on the antimatter version of it, but I'm pretty sure it is identical except that positive charges would be flowing from the positive end of the battery; the Poynting vector would therefore still be the same. But yeah, it's because a moving charge generates a magnetic field, and the two together create a change in the omnipresent EM field, and energy flows due to that change.
EEVBlog's video on it was quite good. Main bits I recall is that the light will turn on at C/1m time, but that near-instant effect will be from capacitive effects and be very dim for some amount of time. He also seemed to say the answer would be different with AC lines, but don't think he went into why that is. So from his viewpoint, the bits about high voltage lines are unrelated to the original question posed
Very interesting points you bring up, and very much seems like Veritasium didn't limit the theories he talked about nearly as well as one should, leading to this "controversy" and so many of these follow up videos
it is a trick puzzle to throw people off track (mislead us). Everyone knows that the speed of electricity is near-c (not at c, but at 0.9c) meaning it indicate propagation inside the wire medium but then he created this trick puzzle to show us that signal did move at c & also jump across wire to mislead us into thinking that signal move outside wire thru fields...
++EEVBlog. The key to remember is that All electrical energy is transferred through EM fields. So for a pair of very long super-conductor wires transitioning from "off" to "on" there would be a "pressure-spike" in the EM fields radiating out at the speed of light(ish). This would go out in all directions with power moving preferentially through the wires. The EM field between the wires would be modelled as capacitive coupling between the wires with the amount of capacitance tending to infinity as the wires get longer. So the light "turns on" about 4ns after the switch is thrown because of capacitive coupling between the wire, but it'll take a lot longer to ramp up to full power.
The DC state is the same as AC at the physics level, but the "transients" in this case are individual electrons being freed in the chemical reaction so the hypothetical "pressure-spike" is unmeasurable.
@@xponen My, my. You sound prone to conspiracy theories.
@@Darxide23 given he’s acknowledged that it was a deliberately misleading puzzle designed to trick people, then I think you’ve been a bit unfair here.
The correct answer fyi was none of the above - the light would always be on, because he stated clearly that it would turn on from any amount of current, so that light could never be off. Electrical drift across the switch would make it brighter before being thrown.
@@Darxide23 my theory wasn't that he wittingly trick us but my theory is that he got tricked himself; after he won that $10k bet for a car that unintuitively use propeller as sail he made a challenge for anyone to deliver an "unintuitive science idea" for that $10k money ,and most likely he fall for this puzzle himself and someone else won his money. He fall for these theory because based on his video I can see he likes to prove people wrong so when people are critical of this theory most likely it made him go head on toward the theory (as a challenge) rather than taking it as a red-flag.
As far as I know, the first transatlantic cable was just single wire. I believe most of telegraph connections by then were single wires with voltage applied against the literal ground. The communication did not exactly rely on closed circuits, rather on measuring changes in electric potential in the wire against local baseline.
The point is, Veritasium was trying to convey the perspective of power being transferred via combination of electric and magnetic field through the space. It's not wrong, it's just a perspective we use to explain the world because it is often useful. But explanation what happens in his experiment or why the transatlantic cable was a failure does not need such perspective and can be fully and sufficiently explained just using usual terms like induction and capacitance (resistance was in his thought experiment ruled out, except perhaps the lightbulb). I'd even say that this power perspective is only useful for stable conditions and totally does not explain why there appears current through the lightbulb right after we turn the switch.
The real way to draw a pair of wires is as a series of resistors on each wire, then between the resistors you have capacitors between the pair, if you have an outer screen, you can then draw capacitors from each wire to the screen
Effectively you end up with series resistors and parallel capacitors along the length. a bit like a pi filter.
Yep, there's all sorts of problems with multiple substations, where i worked we had 5 substations on the main site, one of the cameras on the CCTV system wouldn't sync because it was on a different substation, the cure was to install an isolation transformer in the video line.
Screened cables should only be grounded at one end (the originating end)
We had data between several buildings, the cable had a sceen and armour, when it was installed we had problems everytime there was a thunderstorm. they had grounded the screen to every cabinet, and not used the armour
We corrected it by grounding the armour at every cabinet, ground the screen at main control, then looped the screen through each cabinet conneecting to the next screen, but insulated from the cabinet
And as belt and braces, installed crowbar circuits on each cabinet's data lines
What about capacitor leak? Surely the capacitors should also have very high value resistors between them too? Man this gets complicated... it's almost as if "conductor" and "insulator" are idealised terms, and what the actual universe gives us is more of a gradient, and circuit diagrams are a simple description of what matters to achieve a certain result, and not a recreation of all aspects of reality within the device... huh, who knew?!!
you forgot: Also a series inductance. because electrons have elasticity. The current can't turn on instantly. Than you have the RF cable / transmission line model.
And basically any frequency (even just 0.1 Hz) will behave like RF if the cable is long enough for the wave to show. (Otherwise you would just look at a VERY "zoomed" portion of a ( most likely sine) wave)
@@annoloki I was simplifying, sure you'll get capacitor leak and inductance etc
@@TheRailroad99 Depending on how you derive the DC, you could get ripple which would be ulttra low frewuncy rf i guess
Even if you derive the DC from a battery, there could be induced RF, or interference from the corrosion of the battery terminals.
Have i gone deep enough ? :D
"the real way to draw a pair of wires" - yours is not the real way either. Yours is still an extreme abstraction of what's actually happening. It still fails to adequately explain what is going on, and uses concepts that themselves are also just abstractions. That's not to say it's a bad model, but don't go telling people your way is right, when it isn't, it's no more valid than other models.
I certainly disagree with Veritasium. Take length matched PCB tracks for example. If Veritasium is correct, the data would flow directly from the transmitting device to the receiving device, and mess up the timing. However, that's not the case.
He's being vague when he talks about the bulb being 'on'. I can accept that there would be a flicker due to a surge in current by the switch, but It wont reach a stable continuous 'on' state until the current reaches it.
I think that Veritasium was a little bit vague on what he meant by ‘on’ too. There is energy flow at the bulb nearly instantaneously ( 1m/c s). But this is because of the transience capacitance between the transmission. Given that this would go as the dc circuit reaches steady state and the current becomes stable.
All of what he said is technically true but it’s very contrived setup
That's the correct take. Veritasium conflates transient effects with the steady state situation. There may some energy be transferred directly trough air by inductive and capacitive coupling and electromagnetic radiation, but the bulk of the energy is transported along the wires once the circuit has settled into steady state DC. He is correct that the energy is in the field outside of the wires, but it has to follow the wires closely for DC.
Energy doesn't travel in wires, and the filament of the bulb is a wire, which means the bulb never turns on. We know this to be true, which is why no light bulb has ever been seen to be working, and anybody saying otherwise is in on the whole thing.
@@annoloki The filament is a wire with resistance, which means energy flows from the field outside the wire into the wire and is converted into heat. If the bulb is connected to the source with wires without resistance, then the energy flows as field energy outside these wires and they don't get hot.
@@Theo0x89 Prove the energy flow you are talking about. How do static electric and static magnetic fields outside the wire cause energy to flow inside the wire?!
The undersea cable sounds like a problem Oliver Heaviside worked on and Kelvin's transmission line analysis. Heaviside's development of complex numbers and vector algebra was fundamental to the understanding the delay associated with capacitance and inductance in the cable. It (Telegrapher's equations) also was the precursor to the Shannon-Hartley theorem of bandwidth vs data rate.
Local ground potential differences can be a big problem on the rail network as we often have multiple independent electrical systems operating at both low voltage 650v AC (for signals) and high voltage 25kv AC for traction or 750v DC in areas with 240v residential power. It's not uncommon to see gates sparking where the hinge side is on the rail network earth and the latch post on the national grid earth. It's a bigger issue with access steps where the handrail may be grounded at one end and have a long run to where you step onto them.
Yes, I would agree with that. I commissioned a high-impedance bus zone protection scheme for a double 33kV switchboard at a 275/33kV grid substation, which also accommodated a 25kV supply to Network Rail.
I found I was getting spurious operation of the neutral check relays on the busbar protection and there was often 'standing' current displayed on the relays. I had a theory - which I was never able to substantiate, unfortunately - that the spurious NCHK operation occurred at the time a train passed the substation. I was able to prevent the unwanted relay operation and still have a working protection scheme but never managed to prove my theory.
Only in rail are 6-f'ing-hundred-50 volts AC "low voltage" 😂
@@gabotron94 the EU Low Voltage directive is 50-1000v AC 75-1500v DC. I always chuckle when I hear people talk about "low voltage" as safe.
Veritasium’s example was an outlier from which it is stupidly inappropriate to generalise. His circuit geometry is a basically a pair of big fuck-off aerials and so is dominated by transmission line effects. For any circuit of normal proportions, all signals are transmitted along the wires (and electric engineers will specifically design to *avoid* internal EM transmissions).
VT is correct in deducing that the Poynting vector aims directly from the battery to the lightbulb. The thing is: in his setup the battery side and the bulb side effectively work as coupled antennas so when he connects the battery there’s an instant disruption in the electric field and that is transmitted by the wire ‘antenna’ one meter across to the ‘antenna’ of the lightbulb, transmitting a ‘signal’. However quite some time shall pass before the full flow of current will arrive. And indeed the full current flow *must* ‘explore’ the full characteristics of the circuit: what if there’s a 1 mega-ohm resistor half a light second down the line? When would that come into play in VT’s scenario?
That resistor comes into play 1 second after the switch closes and will then significantly lower the power to the light bulb.
Antennas are coupled AC. A wire stuck on the end of a battery does not act as an antenna. A single rising edge travelling away from the battery would at most cause a single blip on the other wire, but it would also be travelling away from the bulb. I say "at most" because it can easily be dissipated as movement of particles in the air.
@@annoloki But a signal propagating *away* from the bulb and eventually meeting the signal propagating *away* from the battery midway along the conductor is precisely what you’d expect in my scenario.
@@larslindgren3846 No. The Power going to the bulb *_IS_* low until that point, and then just doesn't increase much if there is a resistor.
The only reason he gets away with his "lights almost instantly" claim is because he specified the "the lamp will light at ANY current" which is not even possible in theory.
In a much more realistic scenario with a real 7w LED lamp, I calculated that it will reach 80% of its nominal brightness after about 7 MINUTES and 30 seconds, which is when most of us would probably accept the phrase "The light turned on."
Before that, of course the interactions in the circuit do indeed start like he says and there will be a tiny interaction after 1m/c seconds.
Whether you talk about these interactions as radio waves or electric fields or whatever doesn't make that much difference in the end. There are several effects at work and can be modeled in different ways to get the same results in the end.
It's not just directly from battery to lightbulb. It's in all sorts of paths, including EM energy from other sources (so long as energy is neither created nor destroyed). The key takeaway that got lost in the irrelevant noise of Derek's examples is that energy doesn't flow through wires. It's also not just in coupled antennas, which is one reason that example was so terrible. It's true in a perfectly circular circuit, too; the energy traveling from battery to bulb does flow faster than the charge is passed down the wire, but he's also wrong about the energy getting there first - the charge has to propagate through the bulb for the poynting vector to direct the flow of energy into the bulb. Really it's a terrible example with all sorts of confounding factors.
I've kind of been waiting for your input on Veritasium's video. I suffered the very problems you refer to, e.g. how would power transfer along a SWA, or screened cable, how do we only get a shock from the core of a conductor etc. And the comment about not burying cables due to losses - when cables are regularly buried! His video just didn't seem to tally with everyday experience. Glad you had something to contribute on the matter.
Just to chip in on this - the electron doesn’t know it’s surrounded by a screen - it will produce its radiation because it has too, when it moves. The radiation will affect the next electron in wire because it has to, when you place an electromagnetic field over an electron, it has to start moving. That you’ve wrapped an em shield around the wire doesn’t matter, you have just confined the relationship to within the wire but the EM radiation is still where the energy actually _is_ .
I remember that whilst attending meetings of the Rugby Amateur Transmitting Society (RATS) when it used to be held at Rugby Radio Station, now sadly demolished, when certain members used to use the trick to light up the carpark by merely placing a fluorescent tube in the gutter of their car, and keying the rig in CW mode.......Magic 😊
Regards, Keith (G4TDA)
I have a piece of the mast somewhere in my home. I was shown around the building by a BT engineer while it was being decommissioned.
At our last house, we had to call BT 3 times to stop the crackling on the phone line (each time getting the dire warning that we would be charged an extortionate fee if they didn't find a fault). Local cables were changed, terminals, tightened, but It finally turned out to be galvanic action on terminals in a remote cabinet. Wasn't very impressed with the fault finding, but don't have that problem in our new home- now have full fibre installed.
Just waiting for Veritasium to say that our internet signal is not actually coming through the fibre optic cable!
PS. As told during my days in the CEGB, Overhead lines are strung from Transmission Towers, Pylons are for mooring Airships!
(BTW, the original definition of a pylon was an Egyptian Arch)
I think EEVBlogs had a good take, In short there is the school of Physicists and the school of Engineers. Physicists usually have a grasp on how it really works, Engineers have a better grasp on how to apply it in the real world. I think we, watching your videos, are mostly of the engineering school of thought, but Veritasium is from the physics school of thought.
From the perspective of the school of physicists: by Veritasium's definition the bulb would be "on" even before the switch was closed. This is because Veritasium defines "on" as happening when *any nonzero current* flows through the bulb, no matter how small. Johnson-Nyquist noise, created by the thermal motion of charge carriers, constantly creates tiny, fluctuating currents in anything that's not at absolute zero. So the lightbulb *always* has some tiny amount of current flowing through it, both from this and from incident EM radiation from the rest of the universe, and is, by their definition, always "on".
@@probably_someone000 what if we ask about the soonest time that the expected current is greater than it would be if the switch hadn’t been closed?
@@drdca8263 That definition still has problems. Johnson-Nyquist noise is a random process with a roughly Gaussian amplitude distribution for any finite bandwidth. As such, its instantaneous amplitude has some probability of being arbitrarily high (or at least, up to a height at which the underlying model becomes invalid). So, if you set some reasonable value of "expected while switch is off", there will be some instant, if you wait long enough, at which the bulb will spontaneously be "on" by that definition even as the switch is off.
@@probably_someone000 by expected value, I meant the expected value of that probability distribution. Not comparing the actual value in one case to the actual value in the other case, but the probabilistic expected value in the one case vs in the other case.
(I suppose before you said it was Gaussian I didn’t know that it had a well defined mean, but it seemed a reasonable assumption)
Edit: of course, a device can’t activate when an expectation changes, so I’m just talking about defining an amount of time, not describing something that could possibly be observed to happen at a given time)
(Edit2: so, to make the description more concrete: suppose that for each n from 1 to 5 * 10^9 , you run, a bazillion times, two versions of the experiment, one where you flip the switch and one where you leave it unconnected, and in each case after n nanoseconds, you measure the current where the “lightbulb” would be in the original. Then, you take the average over all bazillion trials. Then, compare which average is higher.
As you take the limit as “a bazillion” goes to infinity, what is the first value of n such that that no larger value of n had the one with the switch not flipped have the higher average?
This many nanoseconds is the snout of time I mean.)
He's from the RUclips school of thought.
One the best vids you have done!
To expand on theatre lights, they usually use DMX as the data transmission type. DMX uses a differential signaling standard called RS485. The switching of polarity is great as when the two signals are combined at the dif amp receiver, in phase noise is cancelled out using common mode rejection. The same applies to balanced audio as well. Something so many in my AV industry take for granted. A fire and forget transmission type, so I wouldn't rely on this for mission critical events.
I think VeritasIamNot did a very good job of making click bait, ensuring that lots of people would interact with his video and everyone would be talking about it, thus driving the algorithm higher, by being "accurate" but leaving out key details.
For instance, most of what he talked about and made sound like it's stuff people don't know about, is actually well known in all Transmission Line Theory, which everyone from RF engineers to PCB designers have to take into account.
And his entire example had nothing to do with the light year length of the wire, but rather the 1 meter spacing between the two sides via capacitive and inductive coupling, which happens right next to the battery and light, and doesn't go to the end of the wire.
In other words, the results would be entirely different if it was a loop rather than balanced transmission line on spacers.
Also, what he said about the nearly instant current flow would not have been enough to illuminate an incandescent light bulb, that would have to wait for the current to flow along the entire length of the wire, but what he was talking about was something that could only be seen on an oscilloscope etc, and was just that initial low level coupled charging of the capacitor, and not really the current from the battery that could light a light bulb.
So yes, he was pretty full of it, and knew it! Lol
Eevblog had a pretty good look at it.
> what he was talking about was something that could only be seen on an oscilloscope
That's the key thing that confused engineers. Someone said that a dynamics question that does not mention the time of the sampled result is just not a good question.
I love how with this video, most of the electronics channels I watch have somehow mentioned or addressed this video at this point.
Could I suggest a followup video -- your best understanding of how energy is _actually_ transferred along wires? 😸
My best understanding (having had a basic electronics indoctrination 40 years ago) is that electricity behaves like heat. Electrons get excited, hit nearby electrons and so on. The ability of a given material's electrons to get excited defines the conductivity of the material.
I know about EM radiation, but I can't understand how so many people struggle to apply a scale to the concept. I mean, it's clear that electricity comes with electromagnetism, just like, say, a soldering iron will *_also_* heat up my lab. This doesn't mean I can melt solder from a distance or that I can keep my house warm with an iron. Veritasium's "iron" has infinite power and is used on a special kind of solder that can melt at room temperature. See? The solder melts with the mere *thought* of using the iron! :D
See my reply.
Until I watched this it never occurred to me that the coils under the road at the traffic lights are actually like "humbucker pick-ups" on guitars
Thank you - it's the AC component that starts to manifest things outside the wire. This why you can't easily measure DC current with a clamp-on meter like you can with AC.
@@Scodiddly it depends on the clamp meter, my hall effect ones will measure DC current.
Hey, uhm i'm a layman with a little knowledge from back in my radio enthusiast days.
I remember studying the effects of propagation, dampening and all the weird stuff concerning antennas. I specifically remember that thing called "Verkürzungsfaktor" aka nominal velocity of propagation. I mean pointing vectors (is that the correct spelling?) all neat and fine, but there was so much more to consider back then. I don't know if physics changed while i was looking away, but from what i remember is that you can have a potential differential anywhere you want within the limits of relativity at any time you want, but power transfer is a different can of worms.
So yes, that lightbulb would see a different potential, but it would take time for the circuit to match to the demand that voltage would bring.
Like you connect a bulb to mains and measure still 230V, connect the same bulb to a AAA battery and you measure my IQ ;-P
Long babbling short it's a mismatch in internal resistance/impedance of the conductor/breakdown of voltage due to a quasi short circuit.
All i wanted to say is that i thought the Veritasium video made too many omissions to to convey a fringe idea that does not include the change over time in a system. No delta t anywhere.
And actuating a switch provoke some delta U, right?
Poynting. John Henry Poynting. Nothing to do with pointing, which is confusing. Also Oliver Heaviside discovered the concept, and also discovered the Heaviside layer in the atmosphere, which is another thing that sounds like a physical description but is a person's name. Electronics has loads of confusing things like this. For examply the Early Effect. Nothing to do with being early for anything, it was named after James Early at Bell Labs. Similarly, the Gunn diode. And the D.C. Power lab at Stanford University houses the artificial intelligence lab, and named after a person, nothing to do with electrical engineering.
In the description of Veritasium's video, there is a link to a couple slides authored by the Physicists he talked to in the video that delve into the change of voltage over time, I think those slides talk about what you're mentioning but nevertheless, not an EE by any means so I may be mistaken.
POYNTING VECTOR - but we got you meant.
@@alastairbarkley6572 thanks for POYNTING this out ;-)
I'm so glad you made a video for this. I watched that video and it blew my mind. As someone who is still new and learning as much as I can, electricity and just what it is, is really hard to wrap my mind around. I understand the different theories, electron vs conventional, but it just doesnt make sense in my mind. Thinking of it in a different way such as fields or magnetism helps give a different perspective to help my puny ape brain. Thanks for all the videos Clive, you've helped me develop a healthy hobby that isnt slowly killing myself like before. Cheers buddy.
I knew Derek had pulled a thunderfoot and was talking outside his own expertise with authority when not informed correctly when A) "The light turns on in 1/C seconds because poynting vector" when the lightbulb would have no current though it so the cross-product of its own vector would be nothing initially, so not absorbing any energy. The energy coming out of the battery would be charging the wires, and some being radiated into free-space as an RF burst/EM wave. B)The 2 light-second-long loop would be tested for continuity instantly, which is obviously naughty and not how physics works. (I.e. put a switch 1/2 light second out at the end of one arm, when you connect the battery, it needs to be determined if that switch is open or closed before DC current starts to flow, so its at least one second before that information (I.e. the edge of the voltage wave on the wire) comes back to you.
"Pulled a thunderf00t" is the best I've heard in a while. Some of his videos are informative but lately he seems to think himself an expert in every field.
@@daviddavidson2357 What are examples of things Phil spoke about that he wasn't qualified to do so?
There is a radio station I listen to that gets inference when I plug my laptop cord in, when I turn the rear window defrost on in my car, and when I use certain electrical device within a ten foot diameter of a radio. It happens on multiple radios multiple sources of inference that shouldn’t be emitting radio waves and occurs constantly. It is only that station, other stations from the same broadcaster are fine.
Edit: It is FM 92.1 incase anyone was curious.
There's a museum in Porthcurno, Cornwall dedicated to the first transatlantic cable.
Thing is, Derek says "bulb lights as soon as **any** amount of energy reaches it". This is the trick.
And now we have to separate things discussed in this video:
- The initial pulse you get in DC via the capacitor analogy (the two wires being the capacitor) is super tiny, not barely enough to light the bulb if you don't apply Derek's "trick". After that pulse we have to wait to the "real" current of energy reach the bulb.
- Second point - which has nothing really to do with the above, but is just an interesting quirk from the physics formula - is the Poynting vector, which simply shows that Energy flows into a wire (with resistance) (the "wire" can also be the bulb), from the electric field.
There is not really a reason to mix those two things together in one video. The first point is basically a question about how a radio antenna or a capacitor works, the second one is some obscure (and in reality useless) fact that arises from the formula. His video is misleading and puts two topics together that don't need to be in one video. But the good thing is, it makes people think. Although they now think that (all) the energy just goes through the air which is totally wrong.
Now the real question would be, at what point does the bulb starts taking the "full" amount of energy (to make it light in real life and not just with his "trick") from the field.
SWR meters illustrate coupling well. Also, my old RF teacher made me understand how "energy" works. Think of every time you charge up that big electrolytic by connecting it to a DC supply. Now, make one plate a round disk and the other plate a rod sticking up through the middle of the disk. Still a capacitor, but now it's an antenna... That'll charge up just like the electrolytic, but now it chucks out a huge EM pulse while it's charging. Current through the air...
The EM is caused by AC accelerating the electrons back and forth. A charged capacitor does not emit EM radiation.
@@stargazer7644 No, but a chargING capacitor does.
4:50 - sunlight being part of the electomagnetic specturm = I think Veritasium covered it. A light was shone through a prism to split into visible colours and the temperature was recorded by each colour of light. A control thermometer was set just outside of the red wavelength light but it was found to be the warmest. Infrared was discovered.
Here in New Zealand there is a high voltage underground feeder that runs at 220kV and it has reactors at each end to deal with the capacitance of the system.It only goes about 20km, but the capacitive effects are large at that voltage
@Michael webber - is that the feed into central Auckland?
@@michaelharrison1093 yep that’s the one
I work in high frequency RF. Veritasium is completely wrong and we can prove it easily by measuring the electrical length of a RF cable while physically moving the far end.
Take an impulse generator (can be as simple as a charged capacitor), oscilloscope, and good length of coax cable - doesn't need to be much, 15 ft would be enough for a 50 MHz scope. Connect one end of the cable to the oscilloscope plus signal source and short the other end (leaving it open also works, but shorted will be clearer on the scope).
When a spike is injected into the cable, it will propagate down the cable at a little under the speed of light, hit the far end, then bounce back to the start. You will see two distinct peaks on the scope - one when the spike first enters the cable, and one when it gets back from the far end.
Now, move the far end of the cable relative to the oscilloscope and see if the distance between the peaks moves. I will put my entire net worth on the result being No Significant Change.
We have cable which is specified not in physical length but electrical length - wavelengths at a specified frequency - and this is one of the ways it is measured.
I also love Crystal set Radios probably could do with better Earth as I tend to use radiator pipe.
When I was younger I made a capacitor/ Leyden Jar out of large plastic cup for Dice and foil and taped thin aerial in middle and charged it up with static on screen of my CRT Television in my bedroom enough that could feel charge in Air / ozone enough to make my Cat wake up and leave my room, and I got scared was too much so I touched it against the Radiator in my Bedroom and there was a spark and at same time a bang downstairs as it blew the water pipe under the kitchen sink clean off the wall where metal pipe was connected to a plastic y shape pipe junction and flooded the kitchen as water was pouring out so fast, I was in my Bedroom at time so my parents thought it couldn’t possibly be anything to do with me, they still think that to this day.
I saw that he that Veritasium video, and remember thinking that he is increasingly looking for science to explain a hypothesis - instead of the other way around, as it should be.
His explanation of his hypothesis was pretty simplistic, while your analysis of it introduced some complexities that were noticeably absent in his presentation.
I like your take on the real world concept of this much more than I'm comfortable with his simplistic assertions.
Watch IBM's 'A boy and his Atom', to see actual pictures of atoms (fascinating). Veritasium's thing only works because of the changing fields at the moment you activate the switch (turn on transient), so it does end up as an AC /RF problem in a way, a transient contains multiple frequencies (listen to an AM radio while turning on a light).
@@JoshuaNorton Sorry, I have no idea what passive-aggressive means, other than it's something spoken by 'woke' and the geometrically patterned ice crystal brigade say. I'm never bothered by someone being right; however I do think that people with a small knowledge of those type of subjects will only be confused for the sake of a 'click-baity' title, and that does bother me.
@@JoshuaNorton He is technically correct but VERY misleading and really doesn't understand why he is correct based on the video.
@@JoshuaNorton No, he's incorrect. The transient from flipping a switch is not going to carry enough energy wirelessly to light a bulb.
@@RexxSchneider yes it will in his example? He specifically stated any current will turn it on.
@@brendonwood7595 he absolutely understands why he is correct. He fully understands, it's just that the video was very misleading.
Science Asylum's older video on this topic was a lot better than Veritasium's. It is theory, but the context where the "energy is transmitted through fields" thing makes sense (is actually useful) is quantum electrodynamics.
Derek got sucked into a click-baity toy problem which really just doesn't quite work.
PS: Medhi (ElectroBoom) has a great response video to Derek's. Well worth the watch IMO.
Electricity and magnetic fields are interconnected that why they can be explained by an electromagnetic wave. The theory exposed by Veritasiom does not negate the one you exposed. That theory is a further explanation of the how.
In the model that you initially explained where electrons are pushed towards one end of the wire. For that to happen you need to transmit that push from one end to the other so it is like electrons pushing electrons pushing electrons. That can be visualized as a wave exactly as a wave on water pushes molecules in one direction. So you come to the conclusion that the flow of electricity is a wave.
Furthermore, you are certainly aware of the connection between electricity and magnetic fields as you certainly know that electricity going through a wire always cause a magnetic field (that is the principle of electric motors). A variation of a magnetic field can also cause induced electricity in a wire (that is the principle of an electric generator).
So a "wave" of the electricity will cause a "wave" of magnetic fields and vice versa.
Therefore, you come to the conclusion that electricity is an electromagnetic wave.
Electricity is NOT an electromagnetic wave. Steady state electricity does not emit any electromagnetic waves. For a charge to emit electromagnetic wave it must move with an acceleration.
Is it a wave push - or the moving of one electron into a space in the next valent or co valent shell which moves to the next space, now it needs to be asked why that movement of electrons - by attraction or the 'gravitational pull of excess of electrons trying to even themselves out - creates a magnetic attraction. Note that the magnetic field is fairly weak of itself and is only increased by the presences of a suitable material like iron (or better 'rare earth' minerals.
Veritasium's video is confusing and wrong in a number of places that have been discussed elsewhere, but bigclive brings focuses on a bit of the video that has been less discussed. Veritasium's major fault is he dies imply that traditional electrical models are wrong ”lies” as he calls them! The big confusio everyone seems to have is the distinction between charge movent and energy flow. These are two totally different (albeit conne ted) phenomenon. Your wrong when you say waves push particles along, it's the wave that travels not the particles (wether it is a wave in water, air or an electromagnetic). EM waves can move outside of wires, but that does not mean the movent of charge does not occur insude the wire. They are two different things.
@@andy_taylor I know that particles are not moved very far by waves in water. That is exactly why I used that example.
The wave in water is the one carrying the energy while the particles only get slightly pushed in one direction each time the peak passes them. In the same way, the electromagnetic wave is the one carrying the energy in a cable while electrons will only be pushed very slowly
Dave over on EEBlog is the best I've seen. The key to remember is that All electrical energy is transferred through EM fields. So for a pair of very long super-conductor wires transitioning from "off" to "on" there would be a "pressure-spike" in the EM fields radiating out at the speed of light(ish). This would go out in all directions with power moving preferentially through the wires. The EM field between the wires would be modelled as capacitive coupling between the wires with the amount of capacitance tending to infinity as the wires get longer. So the light "turns on" about 4ns after the switch is thrown because of capacitive coupling between the wire, but it'll take a lot longer to ramp up to full power.
Thanks, this explanation makes the topic much clearer for me. None of the videos really made it clear to me that the phenomena was an just an initial “wireless” EM coupling, followed by a “proper” circuit which stabilised much later. No magical information transfer faster than the speed of light; no exotic effects beyond the standard EM formulas.
I have no problem with exploring different theories.
Sometimes a new theory opens the door to new approaches and new technology.
"Crazy ideas & partial differential equations" -- Richard Feynman
Veritasiums Video doesn't explore a theory, it demonstrates a patently wrong interpretation of his.
@T.J. Kong Poynting vector exists where the magnetic field and the e-field exist. It's saying that the flowing electrical energy IS the fields outside the wire. Yes, duh, since in coax, all the RF energy is flowing in the dielectric, not inside the metal. What people simply won't believe, is that the same is true at all frequencies, all the way down to DC. "Wave energy" and "RF signals" follow the same physics at MHz, at 60Hz, and at DC. A 2-wire line can send field-energy to an antenna, or to a resistor such as a light-bulb. And there is no special magical frequency where "RF" becomes "AC," or where "AC" becomes "DC." (What we call "DC" is simply a square transient which lasts for minutes rather than microseconds. It follows the exact same physics as the RF pulses.)
@T.J. Kong It's easy to light the "ideal" bulb used in the thought-experiment, and even a real LED should light just fine: a few volts at 4mA for an entire second, until the main 12V signal makes it back around the loop.
Actually the "transient" is a genuine DC step which starts immediately, then runs continuously for an entire second. So yes, a "brief transient" can be many seconds of pure DC, if we're dealing with millions of miles of superconducting coax or twinlead. (The people claiming that it's a spike, they incorrectly employed ten-foot cables in their simulations, not the thousands-miles cables given in the actual thought-experiment. OF COURSE they get a spike. They made an illegal change, and created a Straw Man to attack.)
In other words, if our transformer coils are 100,000 miles wide, and spaced one meter apart, then the coils are coupled 1:1, and we can send DC through the transformer (actually it's half-Hz square waves, pure DC for one second.) That, or just replace the long 2-wire cables with their Zo resistor. If they were coax, it would be 50 ohms. For 5mm cables spaced 1000mm apart, it's around 700 ohms (times two, since there are two of those placed in series with the bulb.)
It is great to remind people occasionally that we don't know everything and most of what we "know" is actually theory! Great video Clive
It's also important for people to realize, production value doesn't make you right.
People that trust their own intellect too much tend to screw up like Veritasium. You'd be surprised how many "physicists" fail to disprove Flat Earthers simply because they don't have the actual ability to work out the scientific results from the data. In Richard Feynman's biography you'll find some examples of physics book authors, and PhD students, failing in grasping the very thing they were regurgitating with authority. Veritasium would not have embarrassed himself so much had he asked somebody with actual training on this field for feedback.
@@dkosmari No physicist can disprove a flat earther because they don’t have a physics model to disprove - they either try to disprove one of our current models or draw a map that can be disproven by pointing out that their distances in the Southern Hemisphere don’t match reality.
@@PippetWhippet Flat Earthers don't have actual maps for a reason. Physicists should have basic grasp of geometry and topology, at which point it's trivial to understand you can't flatten a sphere without stretching and tearing. Any Flat Earth map will have conclusive pair of points that are extremely separated in the map, but close together in the planet.
Having cables under ground is a reall issue. They have to be calibrates with capacitors to remove the inductive load of the ground. This take a signifcant amput of power even for short runs. This is the main reason power cables is over ground.
For DC cables this is not issue. So dc cables can go under ground, but they have a other problem. Joining them. Under sea cable is made in one go. Ground cables have to be joined in field, limiting the voltage to 350kV.
Now there is some part that is absolutly corect with veritasiums statment. The issue is that he uses a dc source.
If it was a ax source and that amout of cable. It would basically just be a huge antenna.
While the energy would reach the lamp in one meter distance, the voltage would only be a fraction.
When working as a service engineer in London way back when
Parking in a multi story .a little trick we found ( by Accident) when returning to the van , with our tools was to use the (Metal) sack barrow with our tool boxes on to trick the sensor at the entrance to pop out a ticket and lift the barrier. This allowed you to drive your van out and not be charged at the exit. Or pay a minimum charge .I don't know if that would work in to days technically world
Thanks for that, Clive, I now understand the meaning of the word, tangent. 😂
Seriously though, it's amazing how well our models fit with electrical and electronic circuits. It's interesting to pull back the curtain from time to time.
I often go off on tangents.
For the "electrons move opposite of conventional current", I have always though about it that since electrons are negatively charged, when they flow one way, the current moves the complete opposite way (aka, what the negative sign does for pretty much anything)
Probably not theoretically sound, but it's how I committed it to memory.
I’ve always remembered it as holes flow in conventional current, electrons flow in electron flow. Holes are just where electrons used to be, a made up particle.
I honestly thing Derrick made his video knowing it would stir up a hornets nest. He saw what his video about the sailing machine, and then Electroboom vs. Steve Mould videos about the chain fountain effect did engagement/views wise for the science and engineering communities here and found a way to turn it up to 11 with his video. I am expecting him to admit this in a new video any day now.
Or a new one where he turns cheese into gold.
I dunno, his next video on bike riding was also complete rubbish that only applies when the person on the bike stays bolt upright, and turns away from the direction of turn to cause the lean. I watched my own turning after watching his video, and saw no such effect, because it's my primary mode of transport, it's intuitive for me to address the lean by shifting the weight from my body, which you can do far more safely in a narrow lane than beginning with a turn in the opposite direction. I think he got a few things right, and we're now seeing the "return to the mean" of getting things seriously wrong that makes his videos average out to be okay, while he's probably forgotten that being right on the last thing doesn't predict the outcome of the next thing.
I was taught to imagine current as hole flow. Electrons (have negative charge) are repulsed by the negative voltage and jump from an atom to a hole in a nearby atom leaving a hole (the atom missing an electron has a positive charge).
Way back when (1977) I was learning electrical fundamentals, I was given 2 theories on electrical power flow.
1: Electron theory, Electrons move from negative to positive potentials.
2: Hole theory, When an electron moves from one atom to the next, it leaves a hole behind to be filled by the next electron. With the holes moving from positive to negative.
Both theories have them moving at close to the speed of light due to that when one electron is moved from the first atom to the second atom, an electron from the second atom is pushed to the third, and so on to the fourth...
I think that what Veritasium was talking about, is the secondary effects of those electrons flowing.
I `ever realized that two loops are employed for detection at traffic lights until today.
Electrons and holes do not move very fast at all, only a handful of meters per hour. Their effects, however, move quite fast. Consider how fast a wave can travel across the ocean, but really most of the water stays in place, circling up and forward and down and back as the wave passes.
Another analogy is a long line of people waiting to enter a restaurant. Imagine the person at the end of the line gets impatient and shoves the person in front of him, who shoves the person in front of him, and so on. The shove will move forwards through the line and reach the doors long before the last person in line.
It's not secondary effects. He (Derek) explained Poynting very badly, which is a huge part of where the controversy is coming from. Poynting describes the flow of energy, not electrons, and in all cases the energy flow is at right angles to both the flow of the charge (electrons) and the direction of the magnetic field (which are right angles from each other). Energy does not flow along the wire, it flows through the EM field, and it does so at the speed of light. Not _some_ energy, not radio waves or incidental amounts of energy from inductive current. All electric/magnetic energy.
On the original video it's really a bit of a trick question. He sets up the problem like we are assuming a basic DC condition but the "gotcha" is that he has then applied AC theory. As soon as capacitance and inductance is brought into the equation then what he says is technically correct but in a really round the back sort of way. Conventional Current for me thanks.
I believe Derek Muller of Veritasium IS RUclips. His 20 minutes video caused so many airtime by other youtubers, so many videos made to confirm or counter his views, sold so many ads. It must be that way ... Derek, give me that Dislike count back!
Correct, Clive. For most practical purposes as it applies to electrical/electronic engineering applications, skin effect is insignificant and conventional current flow is used. Skin effect doesn't occur at DC, because there is no electro-magnetic field created.
Transmission lines are impedance matched to minimise loss. At 1GHz and above, waveguides are used as skin effect does become significant. You can see a wave guide at work, by looking at the ends of a live optic fibre cable, since light is part of the RF spectrum.
Your thoughts make a lot more sense to me than Ve's video. I know his whole thing is being smarter than everyone else (and maybe he is and he's right) but the issues you brought up makes a lot more sense, And comes from real world lived experience, not theory. If you asked me who I wanted to do a critical wiring job; a theorist or an experienced electrician, I'd go with real world experience every time.
The parasitic inductance and capacitance you mentioned are distributed along the length of the cable, as is the resistance. That is why we have transmission line theory to figure out the effect they have.
They were a problem for telegraphy (and later telephony) before we had transatlantic cables. Their effects are mitigated, to some extent, by adding inductors. From memory, I think Heaviside played a part in that.
Yep, Oliver Heaviside and also Oliver Lodge. A good book is "The Maxwellians".
0:40 Has anyone seen an electron? What does "see" mean? Optically? Well yes and no. No in the sense that electrons are too small to be individually resolvable optically. But yes in the sense that the reflections from objects that make them visible are essentially due to the interaction between the incident light and the electrons of the object. But beyond that answer, what we know about electrons comes from many types of experiments that indirectly reveal the nature of electrons (and atomic scale particles in general), some of which translate into commonplace devices where the electrons behave in a well-understood fashion, such as in vacuum tubes. And of those, the CRT is a particularly visual example.
In another sense, electrons are the _only_ thing we ever see. Every photon your retina has ever captured was emitted by an electron, absorbed by another electron, and then shuffled into your brain by a series of other electrons. It's all electrons.
@@oasntet - I thought it was all turtles, all the way down.
@@oasntet Hahaha -- you have a point! Though actually it is possible generate visible-wavelength photons from accel/decel of other particles, but most that we see are from electron transitions (well, electrons in conjunction with host atom).
Oh Clive, this shows the difference between engineering and science. The science is consistent regardless of any one dimension (e.g. frequency), so asserting it doesn't (may not) work outside the familiar radio (or higher frequency) range is starting to encroach on flat earth territory. Much of the familiar world, and the simplifications we make for early learning or "good enough" for everyday engineering become extremely counter-intuitive when you dig deep enough; counter-intuitive is not wrong if the evidence supports it - we just have to change our understanding of how the universe is actually working (to more closely understand reality).
Fluid mechanics taught me that simplifying assumptions are sometimes required to do anything useful.
While technically the answer is always just: 'solve the Navier-Stokes equation' that might not even be mathematically possible. You need to use simplifying assumptions like laminar or turbulent flow, steady state or not, etc.
If you ever did simple optics calculations you probably used a similar idea. Most of the equations use the small angle theorem where sin(x)=x to make them easy enough to solve by hand. It's pretty much true for small angles, so it works and you get to cancel out some nasty bits of the full equation.
So basically, Clive is doing this. The science may say that it technically applies, but his intuition is that it is not a significant factor until you get up to higher frequencies. As far as I know, it does not apply in DC steady state at all.
It is important, by the way, to always list and justify your simplifying assumptions. Just like drawing a Free-Body Diagram with axes and force directions is important in normal mechanics.
Tl;dr: a correct equation that cannot be solved is useless. Simplifying is sometimes vital, and one of those is that you can ignore the EM effects of 12V on a wire 1m away for a low frequency circuit.
I don't think that Veritasium's theory is wrong. The Poynting vector is a well established quantity in electrodynamics and there is broad consensus among physicists that the Poynting vector does indeed describe the energy flowing through / transported by electrodynamic fields. Therefore the theory, that the energy does actually flow through the fields around wires instead of the wires themselves is in agreement with dozens of electrodynamics textbooks and is a direct consequence of Maxwell's equations. Arguing against this theory would mean to argue against Maxwell's theory: Good luck with that!
However I absolutely agree with you, that the examples mentioned by Veritasium were kind of weak and did not necessarily support his theory. As you have quite beautifully explained in your video, there are other, simpler explanations for all examples mentioned by Veritasium. Especially the fact, that there are underground power lines as well, seems to discredit his reasoning behind overground power lines.
However, just because his examples were weak does not mean his theory is wrong. Again, his theory is based on well established and undisputed electrodynamics. It stands on such a solid theoretical fundament, that the lack of good examples is not enough to discredit this theory. At least in my opinion.
V's theory is poorly thought out and even more poorly described. As presented both the lightbulb in the circuit and an unconnected light bulb would be lit at exactly the same time due to the capacitive and inductive leakage as the circuit pulses on closure of the switch. Upon reaching the steady state the lightbulb not connected to the circuit would no longer be "lit" yet would have those field lines not passing internally in the wire also passing through it. This demonstrates clearly that the internals of the wire are having a massively larger effect on power transfer than the external fields that also pass through the unconnected bulb.
Electroboom made another "debunking" of the presented theories; it sounds very reasonable. Main issue is the fact that Veritasium uses a fictional light bulb, activated by the slightest of currents. There is *some* charge moving through the bulb, but depending on the geometry, the initial current spike from the transmission line would be extremely small. It would only turn on fully after 1s, as by that time, the electron wave has reached the bulb, creating the magnetic field required to transfer the full energy. Before that, the coupling is based on capacity between the two wires, which is tiny (two wires, 1 meter apart in air have almost no capacitance between them).
To get an EM wave, you have to accelerate an electron. That happens for an instant when you first flip the switch on a DC circuit, and it happens every time the electron changes direction following bends in the wires. It happens every time the voltage changes and the drift velocity of the electron changes. But for a straight wire with a steady voltage and current, no EM field is created because the electrons aren't changing velocity. To generate a constant EM field, you need AC where the electrons are constantly accelerating (deceleration also counts as acceleration). Resonance with the wavelength also enhances the effect quite a bit. That's how antennas work.
I think the biggest problem for undersea and other long cables is that the cable posesses series inductance and capacitance between conductors and/or ground. This forms a low pass filter and the leading edges of the data pulses get slowed and the pulses can no longer be measured. Resistance isn't a real problem, just fit amplifiers or start with a higher voltage. Same reason that undersea power transmission is usually DC. Long cables are too lossy to AC.
Signal, reflections are also an issue, hence terminator resistors at both ends. Crazy complex science. Quite frankly, it's not good toilet-reading material at all.
Long cables are too lossy at AC? That was the problem Edison had with dc surely? Crank up the volts, reduce the current and I2R losses are smaller. At 50/60Hz L and C is a minor issue over long distances.
@@bigclivedotcom Bergeron diagrams are your friend. Reflect upon that.
Oh. He was Channel Islands. Different crown protectorate from you.
@@robertbox5399 - in a shielded underground/undersea cable its not that easy
I believe that the reason cross country power cables are strung so high is to stop the extremely high voltages arcing to ground through items coming close enough to create a spark gap. There are numerous instances of wildfires being caused by hot transmission cables drooping close enough to the ground due to heat from the environment and current flow to start arcing to vegetation that has grown due to lack of maintenance around the line paths.
Unfortunately, in the last few years, here in N. California....people have died, small towns completely destroyed.....poorly trimmed trees arcing at the powerlines above. The cost in the end, 'Guilty' of 64 counts of manslaughter, huge $$ in fines....was much higher than just trimming the trees, and it's still occurring here, in N. California, USA.
I think the main misconception is that energy is transferred across wires in the first place. Even with the conventional theory, that does not hold since power is voltage times current and there is no voltage across a single wire. In the battery example, you can't point to a specific place where the energy is flowing since the current is flowing through the wires but the voltage is across the wires. But that doesn't prevent us from designing circuits, we can simply calculate how hot the wires become using current and if the isolation will hold using voltage.
The pointing vector theory is certainly not disproved with any of the examples, but rather that it is just not practically applicable in everyday electronic design. Veratassium was plain wrong by his application to the ocean cable and he is very annoying by intentionally leaving out the fact that conventional theory simply follows from the Maxwell equations.
You can't have a current without a voltage difference in any wire that has resistance (and generally speaking, they all do). There is a voltage across a single wire if there is current flowing - it's just usually ignored when talking theory. Every wire dissipates power, and has voltage drop.
The Veritasium's video has some errors but the basic consept is what has been taught exactly like that for a long time already to (all?) electrical engineers. Nothing new there. EVVblog also has an easy to understand video about Veritasium's video:
ruclips.net/video/VQsoG45Y_00/видео.html
@@tkermi True, but everybody seems to ignore the fact that we are all used to calculating power by multiplying the voltage and current (at the source or load, which can be the wire itself) but never ask ourselves what the exact path is that this power takes when designing circuits (including wiring circuits). I think this is mainly because it is irrelevant. Veratasium states that we are wrong about the way we thing about power flow, which everyone is reacting on, but I think we rarely thing about power flow in the first place. All we think about is current and voltage, and we only think about power when it is generated or dissipated. And yes, most (all?) electrical engineers think about the magnetic fields with relation to current and the electric field with relation to voltage, but again power is irrelevant most of the time.
@@tomvleeuwen I totally agree.
This was an awesome video. I hope all these various RUclips responses get to him at some point so that he can do a video to address all the points that people brought up. He's certainly not completely wrong but there's nuance here I think that he would appreciate.
I think you need to bear in mind a couple of things:
Theory in a scientific sense means 'we've tested this, a lot, and it makes the best sense of what we can see and allows us to make predictions', which is very unlike how the general public use theory ('I have a vague idea that might be right).
An electron is just the name we give to a collection of characteristics that seems to behave in a certain way, and how we understand those characteristics has changed vastly over the last 100 years - as Dara O'Briain says, 'No, Science doesn't know everything, if it did, it would stop'.
This
The reduced load the battery sees at the moment the switch is thrown is Ibattery = Vbattery/(Rbulb + 2*Zo), because there's two lines attached in series with the bulb. They have a characteristic impedance (Zo) defined by geometry. In this case it's about 700 ohms per line. So the impedance of the lines will act as current limiting elements of about 1.4 kohms until about 1 second when the reflections begin to stabilize. Eventually the line impedances drop to zero and the battery only sees the bulb alone.
It would basically look like 1) dim bulb as initial wave fronts propagate down the line sections (but YES occuring in 1/c seconds) 2) flickering with an approx 1Hz period, with bulb progressively brightening as reflections interact 3) bulb achieving full brightness as steady state is achieved
The point veritasium makes, is that Capacitance inductance Resistance and the other concepts we use in electrical enginering, are a semplification of what is really happening, which is the interaction of the fields with themselves, the wire and the surroundings.
So you are kinda trying to explain why relativity is wrong, using newtonian gravity which is a semplified subset of the theory
But electrical engineering concepts are as wrong as Newtonian physics. It works for almost everything with incredible precision. No sane engineer will ever use Maxwell's equations for something that can be accurately described by the usual paradigm. They still learn them of course, because devices that work with fields need them. And even then, it's beneficial to simplify models from Maxwell's equations so it's possible to use them with the regular circuit paradigm.
@@gustavrsh I see you did not understand my comment at all
As a lighting technician (for theater) I'm always shocked and excited when someone talks about my job. Can I ask, why you reached for that as an example? I mean, its understandable enough, especially how you describe it, but not exactly commonplace. And do you have more videos related to that topic?
Also, you probably know this and didn't include it because it wasn't germane, but data cables for lighting networks use two lines for signal and a reference voltage cable which further helps to distinguish the signal from noise.
Search my videos for the word tattoo.
Make no mistake, Mr Veritassium knows much better than this. He even mixes fixed-state field equations with flow-based effects, which he has previously shown that he knows full well that you simply cannot do. I actually suspect he's just being as controversial as possible to get more fame - i.e more money. As we all know, truth is no longer something that matters. Only opinions and internet fame is important.
I would argue with you, but he used the word "lies" (or "lied" maybe) which seems so counter to his usual attitude, almost like he's trying to enter the market of the conspiracy nuts, anti-vaxers etc... he may as well have said the earth was flat.
"Post-truth" is just historical revisionism. Post truth is the era where a chunk of people started to imagine that the past was different, and not simply that their exposure was different. Post truth is a sign of pre-ignorance, nothing more. Nothing "matters" objectively, "matters" is subjective, it has to matter TO something/someone. Objective truth does it exist, but it is foolish to believe you can know that you have it; the defining quality of being wrong is that it feels indistinguishable from being right.
I think veritasium oversimplified it too much but in some sense it is correct. However all circuits show a characteristic impedance which varies with the size of the wires and the distance between them. Now this characteristic impedance can be modeled as distributed capacitors and inductors and so it is easy to understand that there will be a current flowing in the circuit the instant the switch is turned on and if there is a lightbulb in that circuit it will receive a current. This current will be the voltage divided by the characteristic impedance. So if the voltage is 10V and the impedance is 100 ohm for instance the current would be 100mA. But when enough time has passed and the wave has traveled all the way to the end the wave sees the true impedance of the circuit and so the normal ohm's law applies. Note also that it will take double the time for the battery to see the true load because the wave has to travel all the way back from the load. It is basic wave theory but I hope it makes sense for anyone getting confused. In short it is oversimplified.
Heisenberg's Uncertainty Theorem says you cannot know where matter is and where it is going at the same time.
If you disagree, don't just dismiss... debunk.
Well done, Clive. Thanks.
Stopped watching Veritasium a good time ago, seems like he's still into "quack-science" (take some pieces you like, ignore what doesn't suit you and come up with your own).
Btw, protons, neutrons and electrons aren't the smallest building blocks - but when those things are explained by true scientists I tend to get a slight headache.
(Sabine Hossenfelder and Sixty Symbols are two good channels in my opinion if someone wants a fact induced headache)
The very channel name "veritassium" screams crack science, and I suspect his latest nonsense benefits from the idiotic removal of the dislike counter.
Tur shitt
I don't think Vertiasium was wrong, but I think he presented the information in a purposefully ambiguous way. I think what he's describing is inductive coupling between the two sides of the circuit (because the length of the transmission line is so much longer than the distance between the ends). Therefore, when the switch is turned on, the wave front of voltage change heads along the cable at nearly the speed of light. This wave front is nominally square, so it has a lot of high frequency components to it. This high frequency energy will be transferred into the "return" portion of the line and, assuming your light is very efficient, it will light up. You won't be getting a lot of current, but you will see the current rise long before the wave front has had a chance to get out to half a light year and come back. In fact, the two lines don't even have to be connected, it just means you won't ever get the full current and the wave front will hit the open end of the cable and bounce back towards the source. There's probably some capacitive coupling going on as well, but I think the inductive part would be greater.
Also, it's important to remember that he's talking about the transfer of _ENERGY_, not electricity. Electricity is carried in the wires, but the energy is carried in the fields surrounding the wires and that energy can be picked up and syphoned off by nearby wires.