As many people here comment, (also IMHO) you are the best tutor i've ever listened to. ... Your explanations are gold. Pure gold. Im enjoying it so much.
RIGHT? This guy is utterly amazing. If I manage to invent/design something I'll be including your name on the patent! Since I was a young boy, I've always felt that the future of transportation, among other things, will be dictated by some manipulation of the EMF. These videos have sharpened my understanding of many things, and for that sir, I thank you.
If you're looking for the next wave of technology then understanding magnetism, other than what is presented, is vital. There is great explanation in these videos and only helps compound the proofs of more to the equation than meets the eye. Viktor Schauberger and his work(books, patents;not nonsense videos people post about him today) will help anyone on this path.
I must say that you have hands down the best tutorials for A Level physics. What I love is that you don't leave out the important maths that is involved in learning these concepts (the a level physics syllabus has a suprisingly small amount of math involved)
Covers every single point in the syllabus in a simple, easy to understand way. I learnt more in 45 minutes than what we learnt in 2 weeks of lessons. Thanks!
Your videos have helped solidify my understanding of electricity principles. I am delighted. Thank you so much for taking the time out to publish these!
Yes. If you go to my A Level Revision playlist you will find that videos 29-38 fit the bill. There is also a separate playlist on quantum mechanics with several videos at a deeper level than A level.
All A level videos are AMAZING!! Badly needed these explanations! :) Thankyou SOO much for this. Can't thank enough :') Your explanations are great. Concepts are perfectly clear now! Stay blessed, sir
You sir are an excellent teacher! I have watched, read, and listened to many of these concepts many times over the years and while I understand a good bit fairly well by now, many points you went over I just now finally can understand thanks to you and your explanations. I still plan to watch this again and practice the math by hand, but you explanations make this complicated subject MUCH easier to ingest. Thank you VERY much for this and your time!!
Just wanted to say thanks for your super clear videos! I can't get over how you make complicated topics seem extraordinarily simple. (I'm more so referring to your video on how you derived Maxwell's 4 equations, but still great nonetheless!) As an electrical engineering/physics major I am thoroughly enjoying these videos.
i graduated high school in 2005, trashed physics at A-level in Hong Kong. now im getting older and like to revise on these stuff. I wonder if i had a teacher like you back then, i wont be where im sitting now. Thanks and i must say, you are a great teacher!!! Ray from Australia
Dude seriously its good to hear that you still have interest in something that you were not good at. People get scared from maths or other subjects at which they are not good however when you study from scratch and make notes and collect other helping stuff you can easily cover any subject at least this is what i believe in. Good to hear that you haven't given up even though you might never have any relation to this topic in the coming years.❤
Good questions. More about technology than physics. The windmills have a very clever gearing device which is capable of self adjustment to ensure that the turbine itself produces electricity at the appropriate frequency. The entire national grid monitors demand on a moment by moment basis and can switch in or out additional generators as the case may be.
Thank you very much for your effort. I am a civil engineer, I wish I had you as a teacher in college courses, I might understand AC today! Thanks again
I am a high school physics teacher and I have listened to a lot of RUclipsrs derive Maxwells equations and you have done imho the best job that a high school student can understand
You will get hurt if you hold the neutral wire. Please don't try it. In the UK the colours are red/brown for live, blue/black for neutral and green/yellow for earth. If you touch either the live or neutral you could get a shock.
Super Tutor... helped me greatly, always struggled in college with electronics & the math side of things... if only they had the staff.. but its all coming back and makes perfect sense. thankyou
Well spotted. At 3:57 it should indeed be the right hand rule (rlght hand for generators - left hand for motors). I have made an annotation. Thanks for spotting this. As far as your second question is concerned, unless there is something I have missed an LED will light only when it is forward biased (ie the current flows in the forward direction thro it). Otherwise no current flows and the LED doesn't light. Perhaps there is more to it in your text book. Is it something to do with decay time?
Yes that's true but the Capacitor holds a much more steady voltage so this is the steady voltage which applies even if another voltage source in the circuit falls.
Yes, I could see that was your point. By the way, out of curiosity I looked at the web for other accounts and other graphs and was astonished to find this to be a common error. Of course the square root of the power would look like the absolute value of sin, which may be in the back of people's minds. Anyway, as I said, otherwise, I thoroughly enjoyed your lesson!
There is a difference between a generator and a motor. In the former case you turn a coil in a magnetic field. There is a phase difference in this case between the maximum flux linkage and the maximum current. in the case of the motor current flows in the coil in the presence of magnetic field causing the coil to turn. In this case there is no phase delay between the maximum voltage and current.
Thats a great video! But you might have made a mistake. In the beginning of your tutorial, when you determined the direction of the current in the coil of an ac generator when it's turned in a clockwise direction, you used flemmings left hand rule. Instead, you should have used flemmings right hand rule. If you did so, the direction of the current would be opposite to the direction you specified. This is all because in ac generators, the induced e.m.f follows the Flemmings right hand rule.
Rudra Ghosh He used left hand rule to find the current direction from the direction of the external magnetic field and the direction of the force acting on the loop of wire. This is correct since the right hand rule works for the cross product of the current and the external magnetic field direction, essentially giving the inverse.
Thanks alot DrPhysicsA... Your videos are extremely helpful.. more so than attending a physics class... because you explain everything so well and clearly. :D
Excellent - Thank you very much. I think some explanation is needed on the two back diodes on the FWR(@41:18). I guess the two back diodes 'meet' at DC Ground?
I would point out that the representation of the Sin squared waveform (explained from around 19:44) is incorrect. It does not look like a full rectified sine wave - in fact it is a sine wave of double the frequency, centered at 0.5Vo. That is where the average value of 0.5 comes from (since the average of the sine wave component is zero).
the root mean square is the average voltage and average current that the resistance load can sense , since it doesn't detect a change in the direction of flow , of current or voltage. unless adding a magnet to the load , it starts sensing the change and starts motion
I'll put it on my "to do" list. Meanwhile have you seen the excellent videos of Leonard Susskind's lectures on String Theory which you can find on RUclips?
You have some highly educational videos! i'm watching these to refresh my school from a few years back and just out of general interest in understanding electricity :) thanks
Sir I have a small question, when you were discussing the topic of transformers, you said that the voltage in primary is given by Vp= Np*rate of change of flux, and voltage in secondary is given by Vs=Ns*rate of change of flux. Now my question is: in secondary, it makes sense that the voltage induced in it is given by that formula, but why is it so in the primary? since the primary voltage is not dependent on induction at all. Hope you understood my question.
Sagar - In this case the V^2 term applies to the voltage in the wire, not the load. It is better to think in terms of the formula P=I^2R (1) for power dissipated in the transmission cables. Since P=VI, if we double the voltage that we are sending down the cable, to get the same power at the end the current is halved. But, because of the I^2 term in (1), the power "wasted" in the cables goes down by a factor of 4. Or look at it another way - we need a 1/4 of the copper to transmit the same power. The downside is that we need more insulation, but that is cheaper, and lighter than copper. In many cases we can even rely on air to provide the insulation.
Re Q2: A filament bulb on an AC circuit is being turned on and off at a rate the same as the frequency of the alternating current, for example 50 times a second, because this cycle is so fast the filament does not have time to cool down and loose light output. An LED (Light emitting DIODE) only allows current to travel in one direction, the light is not produced by heating a filament so as soon as power is cut the light stops. On AC this will happen for every negative voltage cycle.
I'm not sure if someone in the comments has said it or not, but PLEASE do not just stick a large cap in the circuit! You'll waste a lot of power that way. If you were using a Three Terminal Regulator, then the larger your Vmin is (the lowest trough that the capacitor discharges too), the more power is on the input of the regulator. A TTR only needs Vmin to be at least a certain voltage above your desired output voltage load, which in the case of the LM317 is 2V. Then to calculate power dissipated by the TTR, you take the power of the input from the full-wave rectifier and capacitive filter minus the expected output power. Only using the Vmin you need rather than an excessive Vmin can lower the abuse your device will take in terms of heat/necessary cooling!
7:45 I have another idea by Maths at this point the current would have passed an angle of 270 And sin270=-1 so that's why the Vmax is in opposite direction :D
hi i love your videos. They have helped me out alot.. Could you please do the unit 4 past paper questions?? i really need help with those especially multiple choice
I see how you derived the formula for the average Voltage in AC at 20:41 and it does make sense. However I wonder what does another way of deriving it really mean: 1. I integrate the equation of Voltage from 0 to T/2 (taking only positive area): Integral[V0 * sin(omega*t) dt] from 0 to T/2. The result is -V0 * cos(omega*t)/omega from 0 to T/2. Evaluating gives me: V0 * T / pi. 2. I take the area under the curve and divide by change in T -- the length of the bounds of integration: V0*T/pi*(T/2 - 0) = 2V0*T/pi*T = 2V0/pi. Therefore I could conclude that the average Voltage is 2V0/pi. However this value is obviously much different than V0/sqrt(2). What does this quantity represent? Does it have a name? Thanks for all your videos, they are great in helping me understanding a variety of topics in physics. You are amazing at explaining things with simple words, yet not abstaining from maths :)
just saying (cuz i love pointing errors out :p) the graph at 17:54 is a mod(sin theta) graph google sin^2 graph for how an actual sin^2 graph looks like
As usual u r just amazing.... but I 've a doubt on the current transmission.... Power dissipated in the wire can also be written as V^2/R . So if we supply the current at a higher voltage in the transmission cables, according to the above equation power dissipated will be large . Can u plz help me out in this stuff...
At 9:00 minutes roughly in the video. you only talked about the left wire in the loop changing direction, what about the right one? Did it get lost in a Blackhole?
Hey! About using high voltage to reduce the loss of power. We'll get less power lost using the equation I^2*R, But what if we use V^2/R? It'll just be the opposite wouldn't it? So how does it work?
I was a government scientist, then a more senior manager. I was never a teacher but I have given lectures on various subjects.
You are such a wonderful teacher Sir. I struggle most in Physics and you've made it almost easy! May God bless you for all your help.
As many people here comment, (also IMHO) you are the best tutor i've ever listened to. ... Your explanations are gold. Pure gold. Im enjoying it so much.
Many thanks.
RIGHT? This guy is utterly amazing. If I manage to invent/design something I'll be including your name on the patent!
Since I was a young boy, I've always felt that the future of transportation, among other things, will be dictated by some manipulation of the EMF. These videos have sharpened my understanding of many things, and for that sir, I thank you.
If you're looking for the next wave of technology then understanding magnetism, other than what is presented, is vital.
There is great explanation in these videos and only helps compound the proofs of more to the equation than meets the eye.
Viktor Schauberger and his work(books, patents;not nonsense videos people post about him today) will help anyone on this path.
I must say that you have hands down the best tutorials for A Level physics. What I love is that you don't leave out the important maths that is involved in learning these concepts (the a level physics syllabus has a suprisingly small amount of math involved)
That's a noble ambition. For A level it isn't necessary to have the full detail which of course requires an understanding of quantum mechanics.
Covers every single point in the syllabus in a simple, easy to understand way. I learnt more in 45 minutes than what we learnt in 2 weeks of lessons. Thanks!
Your videos have helped solidify my understanding of electricity principles. I am delighted. Thank you so much for taking the time out to publish these!
Love every episode from this great guy.
RUclips should have more speed options - 1.5x is too slow, 2x is too fast
1.75x would really be useful here
oh btw, GREAT VIDEO!!
Im thinkin ab 2.5x 😂🤣
Its available now
get off the meth ...
Perfectly said! I absolutely loved this. Very well spoken.
This is the best physics tutorial I've ever seen in my entire life
Fabulous, just what I was needing at this point in my power engineering studies! Thank you!
You are a good teacher . Thanking for posting your video . All your Videos are Good and its helpful to all the students. THANK YOU!
Yes. If you go to my A Level Revision playlist you will find that videos 29-38 fit the bill. There is also a separate playlist on quantum mechanics with several videos at a deeper level than A level.
Aside from the relativistic nature of electron flow, these lectures are very clear cut and easily understood. Very good job!
All A level videos are AMAZING!! Badly needed these explanations! :) Thankyou SOO much for this. Can't thank enough :') Your explanations are great. Concepts are perfectly clear now! Stay blessed, sir
You sir are an excellent teacher! I have watched, read, and listened to many of these concepts many times over the years and while I understand a good bit fairly well by now, many points you went over I just now finally can understand thanks to you and your explanations. I still plan to watch this again and practice the math by hand, but you explanations make this complicated subject MUCH easier to ingest. Thank you VERY much for this and your time!!
Thanks for kind comments. On Pauli, have you seen my videos on Atomic Physics which cover Pauli?
Just wanted to say thanks for your super clear videos! I can't get over how you make complicated topics seem extraordinarily simple. (I'm more so referring to your video on how you derived Maxwell's 4 equations, but still great nonetheless!)
As an electrical engineering/physics major I am thoroughly enjoying these videos.
i graduated high school in 2005, trashed physics at A-level in Hong Kong. now im getting older and like to revise on these stuff. I wonder if i had a teacher like you back then, i wont be where im sitting now. Thanks and i must say, you are a great teacher!!!
Ray from Australia
Dude seriously its good to hear that you still have interest in something that you were not good at. People get scared from maths or other subjects at which they are not good however when you study from scratch and make notes and collect other helping stuff you can easily cover any subject at least this is what i believe in. Good to hear that you haven't given up even though you might never have any relation to this topic in the coming years.❤
This is really good, I searched through all your videos and find those relevant to my modules, much help!
yes!
Good questions. More about technology than physics. The windmills have a very clever gearing device which is capable of self adjustment to ensure that the turbine itself produces electricity at the appropriate frequency. The entire national grid monitors demand on a moment by moment basis and can switch in or out additional generators as the case may be.
Thank you very much for your effort. I am a civil engineer, I wish I had you as a teacher in college courses, I might understand AC today! Thanks again
My A Level Revision playlist should contain most of the material needed at both AS and A2 level.
I am a high school physics teacher and I have listened to a lot of RUclipsrs derive Maxwells equations and you have done imho the best job that a high school student can understand
You will get hurt if you hold the neutral wire. Please don't try it. In the UK the colours are red/brown for live, blue/black for neutral and green/yellow for earth. If you touch either the live or neutral you could get a shock.
This guy is the best i am even planning on not attending lessons just to listen to him
Still watching your videos after 9 years, you're a wonderful teacher
This video is simply awesome. never thought AC Current would be so easy to learn
You really are a hero, great teaching mate!
Super Tutor... helped me greatly, always struggled in college with electronics & the math side of things... if only they had the staff.. but its all coming back and makes perfect sense. thankyou
Actually the paper is white but the lighting is such that it takes on the colour of the walls. Well spotted. Thanks for kind comment.
watch at 1.5x speed. save ur time and use it else where
supermegablurgh 1.25 speed is better. Lol, u got a nice tip, btw. haha!
supermegablurgh 2x speed if you got game
yes r8 thanks
It may be easier for you to interpret.
But it is important to keep the speed such that the flow of ideas must not be too fast to follow.
After 55 years of turning switches ON and OFF I at last understand what really is going on. I think you earn a Nobel Prize for Education!
Well spotted. At 3:57 it should indeed be the right hand rule (rlght hand for generators - left hand for motors). I have made an annotation. Thanks for spotting this. As far as your second question is concerned, unless there is something I have missed an LED will light only when it is forward biased (ie the current flows in the forward direction thro it). Otherwise no current flows and the LED doesn't light. Perhaps there is more to it in your text book. Is it something to do with decay time?
For a generator yes. What point on the video is this? I may have added an annotation to clarify.
Yes that's true but the Capacitor holds a much more steady voltage so this is the steady voltage which applies even if another voltage source in the circuit falls.
Thanks. Laziness on my part. I was trying to show that the sine squared term is all positive, and didnt draw the wave shape correctly.
Thank u Dr physics u r the best teacher u have clear my concepts instead of rot learning
Yes, I could see that was your point. By the way, out of curiosity I looked at the web for other accounts and other graphs and was astonished to find this to be a common error. Of course the square root of the power would look like the absolute value of sin, which may be in the back of people's minds. Anyway, as I said, otherwise, I thoroughly enjoyed your lesson!
Your presentation on Transformers was more than meets the eye :)
There is a difference between a generator and a motor. In the former case you turn a coil in a magnetic field. There is a phase difference in this case between the maximum flux linkage and the maximum current. in the case of the motor current flows in the coil in the presence of magnetic field causing the coil to turn. In this case there is no phase delay between the maximum voltage and current.
Such a wonderful video and quite easy to grasp the basic concept in impedance. Thankyou so much.
Thats a great video! But you might have made a mistake. In the beginning of your tutorial, when you determined the direction of the current in the coil of an ac generator when it's turned in a clockwise direction, you used flemmings left hand rule. Instead, you should have used flemmings right hand rule. If you did so, the direction of the current would be opposite to the direction you specified. This is all because in ac generators, the induced e.m.f follows the Flemmings right hand rule.
Rudra Ghosh He used left hand rule to find the current direction from the direction of the external magnetic field and the direction of the force acting on the loop of wire. This is correct since the right hand rule works for the cross product of the current and the external magnetic field direction, essentially giving the inverse.
Rudra Ghosh He basically gave the non-conventional direction.
Appreciate the effort. Keep up the good work!
Thanks alot DrPhysicsA... Your videos are extremely helpful.. more so than attending a physics class... because you explain everything so well and clearly. :D
Amazing tutorial. Keep up the good work and know you are doing good work paying your knowledge forward.
YOU ARE GOD TO ME! THANKYOU! I DON'T CARE IF I SCREW UP THIS PRE BOARDS BUT I FINALLY GET IT! THANKYOU SIR!
You saved my grades yet again. Thankyou!
Excellent - Thank you very much. I think some explanation is needed on the two back diodes on the FWR(@41:18). I guess the two back diodes 'meet' at DC Ground?
I would point out that the representation of the Sin squared waveform (explained from around 19:44) is incorrect. It does not look like a full rectified sine wave - in fact it is a sine wave of double the frequency, centered at 0.5Vo. That is where the average value of 0.5 comes from (since the average of the sine wave component is zero).
your videos are great, I downloaded most of them. THANK YOU.
the root mean square is the average voltage and average current that the resistance load can sense , since it doesn't detect a change in the direction of flow , of current or voltage.
unless adding a magnet to the load , it starts sensing the change and starts motion
I'll put it on my "to do" list. Meanwhile have you seen the excellent videos of Leonard Susskind's lectures on String Theory which you can find on RUclips?
You have some highly educational videos! i'm watching these to refresh my school from a few years back and just out of general interest in understanding electricity :) thanks
Sir I have a small question, when you were discussing the topic of transformers, you said that the voltage in primary is given by Vp= Np*rate of change of flux, and voltage in secondary is given by Vs=Ns*rate of change of flux. Now my question is: in secondary, it makes sense that the voltage induced in it is given by that formula, but why is it so in the primary? since the primary voltage is not dependent on induction at all. Hope you understood my question.
Because an alternating current has a voltage vs time pattern which follows that of a sine wave.
Very well delivered. Thank you!
Sagar -
In this case the V^2 term applies to the voltage in the wire, not the load. It is better to think in terms of the formula P=I^2R (1) for power dissipated in the transmission cables. Since P=VI, if we double the voltage that we are sending down the cable, to get the same power at the end the current is halved. But, because of the I^2 term in (1), the power "wasted" in the cables goes down by a factor of 4. Or look at it another way - we need a 1/4 of the copper to transmit the same power. The downside is that we need more insulation, but that is cheaper, and lighter than copper. In many cases we can even rely on air to provide the insulation.
Thanks graham.... I was just assuming the entire voltage across the cables... that's so silly of me...
Re Q2: A filament bulb on an AC circuit is being turned on and off at a rate the same as the frequency of the alternating current, for example 50 times a second, because this cycle is so fast the filament does not have time to cool down and loose light output.
An LED (Light emitting DIODE) only allows current to travel in one direction, the light is not produced by heating a filament so as soon as power is cut the light stops. On AC this will happen for every negative voltage cycle.
please note that your sin^2(wt) at 19:25 waves should be smooth as they are actually just -1/2cos waves translated up 1/2
I'm not sure if someone in the comments has said it or not, but PLEASE do not just stick a large cap in the circuit! You'll waste a lot of power that way.
If you were using a Three Terminal Regulator, then the larger your Vmin is (the lowest trough that the capacitor discharges too), the more power is on the input of the regulator. A TTR only needs Vmin to be at least a certain voltage above your desired output voltage load, which in the case of the LM317 is 2V. Then to calculate power dissipated by the TTR, you take the power of the input from the full-wave rectifier and capacitive filter minus the expected output power. Only using the Vmin you need rather than an excessive Vmin can lower the abuse your device will take in terms of heat/necessary cooling!
Excellent!!!
Thank you so much,
ONLY ONE WORD FOR YOU....YOU ARE AWESOME!!! THANK YOU!!!! :)
Hats Off to yuh Sir .. your lectures are Supeeeerrrrrrrrrrrrrrrr Awesomeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
7:45 I have another idea by Maths at this point the current would have passed an angle of 270 And sin270=-1 so that's why the Vmax is in opposite direction :D
All in all, it is an amazing work, thank you!
i like this, your explanations are so very clear
It was quite helpful for me.. Thanx alot sir
few of my concepts got clear after this lecture ☺
a big thanks from tunisia :) your videos are really helpful
I jst luv ur videoes ur xplainations r crystal clear
thank u
Many thanks. Very kind.
Hi, how do u know cutting of magnetic flux is left hand rule? Isn't it a generator?
Can I have all the sheets you've filled so far? :3
Thank you very much for these videos!
hi i love your videos. They have helped me out alot.. Could you please do the unit 4 past paper questions?? i really need help with those especially multiple choice
I see how you derived the formula for the average Voltage in AC at 20:41 and it does make sense. However I wonder what does another way of deriving it really mean:
1. I integrate the equation of Voltage from 0 to T/2 (taking only positive area): Integral[V0 * sin(omega*t) dt] from 0 to T/2.
The result is -V0 * cos(omega*t)/omega from 0 to T/2. Evaluating gives me: V0 * T / pi.
2. I take the area under the curve and divide by change in T -- the length of the bounds of integration:
V0*T/pi*(T/2 - 0) = 2V0*T/pi*T = 2V0/pi.
Therefore I could conclude that the average Voltage is 2V0/pi. However this value is obviously much different than V0/sqrt(2). What does this quantity represent? Does it have a name?
Thanks for all your videos, they are great in helping me understanding a variety of topics in physics. You are amazing at explaining things with simple words, yet not abstaining from maths :)
thanku man u r my savior 💕
Kind Sir, thank you very much for this lesson, do you have anything on balance three phase electric power systems?
Thanks
When i grow up, i wanna be just like Dr Physics!
Brilliant video! Thank you!
this guy explains properly. i just have one question though.... how are you in the uk and using miles???? lol
It is a big blunder to use Fleming left hand rule for generator. That is for motor. Use right hand rule.
Very Good Explanation!!!!
Nice Explanation Sir, Thanks
just saying (cuz i love pointing errors out :p)
the graph at 17:54 is a mod(sin theta) graph
google sin^2 graph for how an actual sin^2 graph looks like
PS. not by any means trashing you . you are AMAZING.just an error i found
@DrPhysicsA, will u be able to do a video on the topic of Torque and Moments of Inertia, and the integrations to do with it?
this is very excellent work,now i have a very clear understanding :D
So in bridge rectifier, what's the use of two diodes at the back? Without them, the function will still be the same. :)
really , you're so wonderful ^_^ thank you
Very interesting and helpful, thank you very much.
to clarify.... for their to be a voltage the current in wire must cut through and be perpendicular to the lines of the magnetic field?
As usual u r just amazing.... but I 've a doubt on the current transmission.... Power dissipated in the wire can also be written as V^2/R . So if we supply the current at a higher voltage in the transmission cables, according to the above equation power dissipated will be large . Can u plz help me out in this stuff...
At 9:00 minutes roughly in the video. you only talked about the left wire in the loop changing direction, what about the right one? Did it get lost in a Blackhole?
You sir, Deserve a like, a subscribe and a share! XD
for low amount of voltage, does cellphone sustain corresponding high amount of current while charging?
Your the best..God bless you!
Hey! About using high voltage to reduce the loss of power. We'll get less power lost using the equation I^2*R, But what if we use V^2/R? It'll just be the opposite wouldn't it? So how does it work?
Very, very good.
Great
thanks a lot, this video is gonna help me pass some tests