Does current convert to heat?
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- Опубликовано: 2 окт 2024
- When current passes through the resistor, there is heat generated. If this heat is generated from the current, then shouldn't current decrease?
Because energy can neither be created nor destroyed!
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For the one electron case, what do you say about the current in the resistor vs current outside? Let the debate begin 🔽
Weird 🤨🤨
@FloatHeadPhysics I think the current will be less across the resistor as compared to the current outside (in circuit) ,in the case of one single electron.
It must be same. Because amount of charge that pass through the resistor will be same as amount of charge that pass through the wire for equal time intervals.
I think the current will remain the same outside the resistor and inside the reisitor becuase current is coulomb's per second or no of e- per second and that thing won't change, as in this situation there is only 1 e- moving around the entire circuit, also it's drift velocity will also remain the same throughout the circuit as the power source remains the same and voltage remains the same.
@@ted89942 I beat you by 33 seconds 😂
El. engineer here. As best as I know it goes like the following. First it should be considered that it takes some time for the electric field to raise the voltage across the resistor from 0 to its stable value. Typically, the voltage jumps at a high order exponentially increasing way to some value above the source dc voltage and stabilizes in an exponentially decreasing sin manner to the source voltage minus the small voltage drop in the wires. Immediately after the initial moment of closing the circuit/starting the circuit, the field starts propagating from the source terminal parralel onto the surface of the wire at the speed of light. It propagates outside the wire, so typically the speed of light in vacuum or air. It starts from the negative terminal and has negative value, so the effect on the electrons in the wire would be to rotate the electric and magnetic moment vector of electrons in molecular and atomic orbitals below the energy level of the orbitals in the valence outer shell. The field can also rotate the polarization vectors of any present polar molecules. This is also a type of current. As the field travels along the wire surface, repelling the valence electrons away from itself, it yanks many valence electrons above the conductor's own band gap to molecular orbitals corresponding to the conduction band. So these electrons travel or their wave functions propagate through the wire along the available orbitals in the conduction band. Now like in your example, let's consider the field after some very short time interval from time zero when it has created an average current density in the conductor cross section of 5, or 10, or any amount of few or several electrons. In the wire, a very small number of electrons have a probability of tunneling to and/or losing energy and falling back in the valence shell. Then they have a probability of being reexcited to the conduction band and so on. When the field reaches the resistor, basically as you said, electrons bounce around between atoms and molecules at a higher rate. This can cause them to lose energy and a higher number of electrons now have a probability of decreasing to lower orbitals in the conduction band and falling in the valence shell. Each decrase and fall result in emitting photons of thermal radiative/radiation energy in all kinds of frequencies, determined by the difference in orbital energy levels each decrease and fall for each material. So actually when the field exits the resistor, it will push a lower number of valence electrons and will rotate the moment and polarization vectors by a lower angular momentum. The field will continue along the second wire to the positive terminal of the source. In the most general case at the contact boundry between the wire and the terminal, part of the field will continue in the same phase along the terminal through the battery out the other terminal again. The other part of the field will be reflected in the opposite direction back to the wire with reverse phase. It will again propagate through the resistor and wires back to the negative terminal. Then reflect from the negative terminal again in opposite phase, this time becoming in phase with the exponentially increased field coming out of the source. It will continue bouncing this way between the terminals creating an interference, which over time will converge/stabilize around a single median stable state within a required tolerance. This field creates the measured voltage drop on the resistor and a kind of constant drift along the along the entire circuit. The electron interactions can be more energetic and chaotic in the resistor. This can cause it to emit more thermal radiation than the conductors and the source, but the average current density can remain the same in every part of the circuit after the field has stabilized.
Hello, I would like to ask if the electrons directly contact the atoms, or if the electrons reach the atomic level and react with the protons in the atoms, causing the atoms to vibrate.
Sir why are u soooooo underrated 🥲.. I can't understand what people are watching if they're not watching you 🙂❤. Thank u so much for your brilliant videos .
And happy Teachers day in Advance 💟💜. U r one of those real heroes , teaching us the essence of science not rotelearning phenomenons and formulas 💞
Please do more videos on electricity! You are an excellent teacher. You should have many more views on your videos than you do.
You know who is the most mysterious person on the universe it's ELECTRON ....so i don't know how he behaves in different situations ...but i want to know the answer ...❤💯
Question: Why Area under Velocity-Time Graph equals Displacement? I mean it's easy to understand for a rectangle but what about a triangle or a curve?
Any shape can be treated to be made of many many rectangles of various lengths ;-)
@@Mahesh_Shenoy is there any way i can visualize it :/
single electron would never move since there is no push from battery.
Motion will only happen when there is a chain of e- throughout the ckt. Right ?
I think battery has all the electrons on one side. Electrons don't really go through the battery, they just return to "their place" using the circuit. So the single electron would only go through the circuit once and calculated current would be lower in the resistor because the electron would go slower and there are no other charges Infront or behind it to balance the speeds out.
Can you explain whether electron collisions with atoms actually occur?
Can you explain why elements connected in parallel have the same voltage?
The elecrons doesn't actually touch anything but they interact through their electric fields like repelling magnets pushing each other.
Voltage is a difference between two points. The voltage of a heating element is measured between its ends. When the elements are connected in parallel the one end of each element and the other end of each element is connected together so the voltage across each element must be the same
Sir, please make a video on Evaporation and boiling?
In details.
please sir.
Is the work done equal to heat dissipated?
Hello. In electrostatics, first the electric potential is set to zero at infinity then we do the derivations. For an example, the electric potential on the surface of a sphere is KQ/R ( assuming V=0 at infinity). Then, when the conducting sphere is connected to the earth, it's potential becomes zero because the potential of the earth is almost constant and assumed to be zero. I don't understand this logic, the potential is already set zero at infinity then in the same problem how can we set it equal to zero for the earth. It would be great, if you could help me clarify this doubt.
Hare , the earth is neutral (not really, actually earth has slightly negative charge but it's negligible) , so we assume that no charges present in the earth , so no charges means zero potential. It's called the conductor is earthed i.e if any charges present on the conductor it moves to ground making the sphere chargeless
Sir I really needed this video
I am glad it helped you :D
Is the drift speed in resistor the same as speed outside resistor in just regular wire?
I think the average drift speed will change inside and outside the resistor since there is only one electron. The electron will experience resistance inside the resistor which will slow it down but outside the resistor it is free to move. This would not be the case if there were other electrons too because the slowing down of one electron would consequently slow down the other electrons too, thereby making the average drift speed constant.
Now, since the average drift speed is changing, the passing of the electron per unit time through a particular cross section will also change making the current different inside and outside the resistor.
Speed of electrons is different from outside to inside a resistor if there's only one electron because in normal case we have sea of electrons and speed is same every where according to car anology.
In case of single electron-
So, as rate of flow of electron is different from outside and inside current is different too.
Love the justification! Hope more participate :)
We all know that voltage is directly proportional to current , so if the voltage across the resistor is different the current must also vary in accordance with voltage .the only thing remain constant is resistance so, hence current is different from the outside current
Can i get your videos of all chapters in class 12 NCERT? .. Some chapters watched in khan academy.. I need all the chapters sir.. Only your videos... Any playlist link sir?
I don't have any, as of now, Manikandan :-/
@@Mahesh_Shenoy it's ok sir.. Thank you for reply.. I always like your way of teaching sir☺
Sir i have some a question related to gauss law and ampere law as ampere law simply the problem of biot - Savart law and gauss law simply the coulomb law but intial laws are experiment based and easy to understand why they look as they look but how ampere and gauss law come to simple solution..
How they come up to their equation..
I didn’t quite understand your question
i don't know the answer but if there is only one electron then the electron can't flow because it have not the definit direction, as we know that in neutral wire the electrons randomly flow which makes 0 pd so if there is only one electron then there is no force that tends the electron to flow in definit direction so there is no flow of electron take place thus there is no current measure
well i'am in 10th class so i am not sure sir.
It would be great if you upload some videos for Jee questions, in which you solve them with pure Logic and Intuition! 😀
JEE and LOGIC can't be in the same sentence :D
@@ted89942 Yeah, I looked up on the internet some questions of Jee, they are actually hard with a lot of calculations. i want to BTech in CSE what should I do :(
@Warrior I would suggest you to go with your ncert book. if you're finding some question/topic difficult then watch the video whether it is of khan academy or any other!
@@ted89942 Ok appreciate your response bro!
@Warrior ncert and youtube simultaneously karo sare basic ho jae ge!
I will use gravitational analogy here. There is a potential energy field around a planet. So if there is a ball placed in space. It will accelerate like 0 m/s then 4 then 8 then 12... So I think that electron from negative terminal will start from v=0 and speed increases till it hits resistor. Then what you told will happen. Then after exiting resistor, electron may again accelerate from 0 m/s to something and hit the positive terminal with some speed. And I think average velocity will be different in left and right conductor and resistor.
Basically we don't understand electricity works at all xd
We do :D
I think it should be explained that current is the number of coulombs passing a point per second and bears absolutely NO relation to electron velocity at all. Also, if the wire is a perfect conductor, then no heat is dissipated in the connecting wire, and there is zero electric field in the wire. The only place an electric field exists (apart from inside the battery) in the circuit is within the resistor, hence there is a voltage across the resistor and hence there is power dissipated in the resistor equal to V^2/R. To even suggest that electrons bunch up in a resistive circuit is misleading and false. Sure, in a capacitive circuit they do, until the induced field opposes the field from the battery.
Sir plz make a video on irodov ques 3.144 and hc verma capacitance example 12? The answers given are different.
Energy has already been spent on the battery to separate the electrons while charging... So I don't understand why you explain the gain of potential energy for the electron as a part of current flowing in the circuit.
Sir is that heat energy radiate out from the wire??
Which type of wave electron is. My teacher told me it is both matter and non transversal wave as electrons come from sun during coronal mass ejection to the earth .
Plzz answer me these questions I'm very confused .
Sir in one of your videos named "How circuit really works"
One of my friend asked you the doubt that we came across while discussing that the movement of electrons is due to the pulling or pushing force
every one including you stuck to the same analogy according to which you imagined the electrons at the -ve end are exerting a pushing force on the neighbouring electron and so on as a consequence the current remains exactly the same across the resistor
As we thought with respect to a single electron which you queried here in this vdo,how the current would be same if that is the case as the free electrons nearer to the +ve terminal should get attracted and then one more question arises willn't that leave the conductor charged!
Although he didn't receive any reply😅
My question is still the same
It will be extremely kind of you if you clear this doubt
Where does the kinetic energy of electrons come from in a circuit does it comes from the potential energy provided by battery as you said or the electric potential energy of charge which gets converted into kinetic energy of electrons when repelled by terminals which i think according to my ananlysis?please sir can you answer this doubt
How to explain the kinetic energy of electron?? now consider a particle or you the observer moving with the same velocity as electron according to you then the electron is not moving at all it is at rest so it does not have kinetic energy according to the definition and it does impart some kinetic energy to the atoms and its giglet mode so according to you the observer you feel heat but according to you there is no kinetic energy associated with the electrons how do you explain that
electric field lines never intersect....why???I mean drawing electric filed at a point just means that if i keep a charge there,it would be deflected at the direction which is tangential to electric field line.....so imagine a intersecting field line is created by two charges ..... if I keep a test charge at that intersecting point the force experienced by the charge will be net force because of two charges....so one force from one charge and 2nd force from other charge u add them(obviously by vector addition) then we should get a net force with a new direction!
I used to think the same!
Will the resulting force direction be tangential to either of the field lines at the intersecting point?
@@Mahesh_Shenoy ultimately the tangential lines represent the direction of force right??? so even if u draw two tangential lines(why two??cuz of two charges) pointing at two different directions...now u treat those tangential lines as force vectors(because it is actually that) and add it vectorially(if that's a word)
also it's hard to find ur videos on electrostatics first chapter i.e electric charge and fields,i mean there is a playlist but that has many videos missingg like in the first video itself u ask us to find electric field lines even though U didn't teach anything about it also there is a video explainnig proof of gauss law without explaining flux or even what is gauss law...although if we search it seperately it comes but in playlist it's not therre...
@@Mahesh_Shenoy oh well idts it will be tangential.....unless one of them is zero
@@mridulacharya8250 So, instead of the 'user' having to do the vector addition all the time, the convention is to do it and then adjust the field directions accordingly.
Otherwise, field lines would be pretty useless. You will have to manually do it. Imagine 100 charges!
Can you please explain why the voltage is constant in parallel and the resistance decrease. Same why u explained the current in series
Hi again professor, I want to ask you about producing light from electrical energy.
_So in the filaments ,it first converts from electrical energy into thermal energy. Then thermal energy is converted to light energy._ ,right? Or is there a something I'm missing?I'd be grateful if you could clear up my confussion here.
Thank you in advance
yes. Hotter the object more light it emits. there is law called stephan boltzman law
when u talked about inductors in ac you said that , and this is absolutely logical , voltage across generator equals voltage aqros inductor . does it mean that inductor has equal voltage att every instatnt as source and it acts in oposite direction , if so that oposite voltages must cancel each other beacuse they are in series . so how current flows in the circuit . And one more question, if the rate of change of current flactuates how voltage across inductor stays same as sorce voltage ?
The one thing missing in the video is the name of that "Electrical Potential Energy" that's converted to kinetic energy. We call it "Voltage".
This answer is more an EE perspective than physics, but hopefully will help you understand what's going on. There's also some pretty fun simple science experiments you can do yourself. Google "CircuitLab" and it will let you play with these things online and see what each part does.
One big thing is you have three ways things can behave. Steady state DC (Battery), Constantly changing waves (AC), and an impulse. The last one is what happens when you first connect the battery before everything's settled down. What we can do is model AC like an impulse from 0 to max voltage, then model it as max voltage to 0.
If you start at time 0, and apply a positive voltage to an inductor, the potential energy means the electrons now want to move. The key is that moving electrons produce a magnetic field,* and inductors are designed to concentrate that field. It just takes a bit to "grow". We also know that a moving magnetic field makes electrons want to move, aka it produces Voltage. The simple, but crazy, explanation is that the new magnetic field that's "growing" from time 0 actually makes a voltage almost equal and opposite to the voltage being applied. It's often described as an "open circuit", but a better explanation is like we instantly stuck a DC generator in there positive to positive, and negative to negative.
As the field "growth" slows, the induced voltage slows, and there's more voltage. Eventually, the field gets as big as possible and there's no more induced voltage. Like turning down the voltage on the generator so current can pass through it. Eventually the inductor looks like just a piece of wire. It's invisible in DC steady state.
Now, what happens when we start reducing the voltage we feed into the inductor? Well, the trick is that the magnetic field is controlled by current not voltage. If the current stays the same, nothing happens! However, what almost always happens is voltage and current are related. Less voltage, less current. Causing the magnetic field to shrink. Once again, a changing magnetic field produces a voltage. This voltage is actually now in line with the change, so going back to that DC generator example it's like we flipped it and are now adding voltage.
The trick is that magnetic field won't have completely gone away by the time the voltage hits zero. As the voltage goes negative, the potential energy means the current wants to flow in the other direction, but the magnetic field in the inductor is causing current to flow in the original direction. At least until the magnetic field is gone.
* See the video on this channel about how that.
Doubt=does electron actually move in circuit
Of course it does
Thanks for sharing! The battery discussion needs to be revised. I think viewers may think electrons are moving in a loop. But electrons do not move in loops. It is just ONE path with a beginning and an end.
U mean battery work like capacitor
@@tasneemraheem8320 correct... The potential energy in a capacitor is stored in an electric field, where a battery stores its potential energy in a chemical form
You are amazing sir 👏👏
This is an amazing video
i think the speed will decrease as there's no electron waiting behind
Also, what happens to the current?
@@Mahesh_Shenoy by definition, current is the rate at which electrons flow past a point in a circuit. i think since there's only one electron, the current throughout the circuit won't be constant. so uh it might drop at the points of the resistor.
Hello sir, I'm finding difficult to understand some topics like "Atomic Spectra" can you suggest me a way I can understand them or how would you do that if you were in my position?
Sir, you explain things really well. Recently I watched your video on why less enegy things are more stable and the explanation that you gave was very logical and it directly penetrated into my brain Sir I have a doubt in Electromagnetism where Newton's third law seems to fail. If you understand Hindi then I have attached the video of that question below. This question was asked by my JEE Physics teacher and he himself is searching for a proper explanation of it from past 3 years, If you could give me your 5-10 minutes to answer it then it would be huge help.
Video Link:
ruclips.net/video/toB2EPoW0TE/видео.html
Thanks for giving me something to think about. I don't have a complete answer here, but from what I understand when it comes to fields, one must look at momentum conservation and not equal and opposite forces as Newton's third law.
Apparently, the momentum is still conserved and is carried by the electromagnetic field. But, I myself am not convinced and I still feel shaky about it.
Video starts at 4:31 😂 unless you really want to listen to 4 min of being told whats not possible over and over again🙄🙄🙄🙄🙄🙄