"Veritasium" (YT) - "The Big Misconception About Electricity" ?

[SiliconWizard]

So now, let's study the same setup, but with a circular wire loop instead of a rectangular one.

[SandyCox]

So now, let's study the same setup, but with a circular wire loop instead of a rectangular one.

I assume we are talking about two circular loops, replacing the two rectangular loops?

The answer will essentially be the same. During the transient energy, in the form of an electromagnetic wave, will reach the bulb after approximately 1m/c seconds.

The situation in the steady state is very different: All the energy is transfered by means of the flow of charge. The magnetic and electric fields (and the Poynting vector) makes it possible for us to measure that energy is flowing. However energy is not transferred through the electric and amgnetic fields.

I am working on a more detailed explanation.

[HendriXML]

I got this one in my recommended list, which has only a few hundred views, so hence I link it here. The first half with formula's I skipped, but the 2nd half shows to me a valid point about electric fields in wires vs air gap when using quantum theory.

[rfeecs]

The first half with formula's I skipped, but the 2nd half shows to me a valid point about electric fields in wires vs air gap when using quatum theory.

I am guessing that she is just explaining the inverse square drop off of the Coulomb force by using quantum field theory, saying it is much stronger between electrons in the wire than electrons separated by one meter.

[HendriXML]

The first half with formula's I skipped, but the 2nd half shows to me a valid point about electric fields in wires vs air gap when using quatum theory.

I am guessing that she is just explaining the inverse square drop off of the Coulomb force by using quantum field theory, saying it is much stronger between electrons in the wire than electrons separated by one meter.

Which would mean that most of the energy is transported through the wire, just as most people would have expected. The video of Veritasium was quite different and seems a misrepresentation of the theory (in comparison).

[SiliconWizard]

The first half with formula's I skipped, but the 2nd half shows to me a valid point about electric fields in wires vs air gap when using quatum theory.

I am guessing that she is just explaining the inverse square drop off of the Coulomb force by using quantum field theory, saying it is much stronger between electrons in the wire than electrons separated by one meter.

Which would mean that most of the energy is transported through the wire, just as most people would have expected. The video of Veritasium was quite different and seems a misrepresentation of the theory (in comparison).

Well, maybe we should start by defining in a strict manner what "transported through the wire" means. I'm sorry, but "through the wire" is not really a scientific concept. That needs to be a little bit more defined that this.
Then looking at various videos and various posts in this thread, it doesn't even look like everyone means the same with that phrase, which is not surprising.

[SiliconWizard]

So now, let's study the same setup, but with a circular wire loop instead of a rectangular one.

I assume we are talking about two circular loops, replacing the two rectangular loops?

Uh. Sometimes, words are poor at expressing simple things. So, what I meant was essentially something like this: https://www.eevblog.com/forum/chat/veritasium-(yt)-the-big-misconception-about-electricity/msg3823973/#msg3823973

With the battery and switch (let's neglect the distance between those two again) diagonally opposite to the load, and R the radius of the circle.

[HendriXML]

If one posts a video about "misconception about electricity", which shows large fields around the wire and is probably a huge misrepresentation of the underlying theory than things don't get better in the common understanding of things.
It seems like the probably vague conception (called misconception) most people had/have is closer to the truth/theory, which would make the video kinda pointless.

[SiliconWizard]

If one posts a video about "misconception about electricity", which shows large fields around the wire and is probably a huge misrepresentation of the underlying theory than things don't get better in the common understanding of things.
It seems like the probably vague conception (called misconception) most people had/have is closer to the truth/theory, which would make the video kinda pointless.

While it's lacking in various areas, the video is still interesting in that it's thought- (and discussion-) provoking. But again, claiming what is the "truth" or not is itself pointless unless getting in a lot of intricate details, which far exceeds what can be done in a single YT video.

One related "misconception" often noticed is the way electrons move in (or through) - again that's unfortunately a very vague concept when put like this - a conductor when current "flows". In particular, the idea that a given electron will move all the way along the conductor, as would molecules of water flowing through a pipe. But isn't that also the distinction between quantum particles and those that are not?

[EEVblog]

I got this one in my recommended list, which has only a few hundred views, so hence I link it here. The first half with formula's I skipped, but the 2nd half shows to me a valid point about electric fields in wires vs air gap when using quantum theory.

Very interesting, thanks for posting.
Nice explanation, sounds pretty solid to me. Quantum probability theory trumping Poynting?
I've sent this to Derek.

[EEVblog]

Because it's likely she isn't going to join in the discussion here, i'll post her response to my question:

[Bud]

Her response does not make sense in its battery near bulb part. The circuit  needs to be closed  in order for the current to flow and  produce the fields. You do not have to believe me, just put your current clump over a disconnected battery terminal and see what it will show you.

[EEVblog]

Her response does not make sense in its battery near bulb part. The circuit  needs to be closed  in order for the current to flow and  produce the fields. You do not have to believe me, just put your current clump over a disconnected battery terminal and see what it will show you.

Let's make this easy and only talk about the DC steady state.
Does the energy flow in the field around the wire, or inside the wire?
If you use classical field theory, it's in the field and the Poynting vectors.
If you use quantum field theory is seems like the probability is that it's almost entirely within the actual copper wire, which to me makes more sense.

[bdunham7]

Nice explanation, sounds pretty solid to me. Quantum probability theory trumping Poynting?

It was rather offhand and not really rigorous and didn't really address the actual question (1m/c or 1 second).  The presentation started to discuss the nature of fields, but then seemed more to only address the earlier part of Derek's video. Perhaps that was the intent.

[Bud]

 @EEVBlog : Not sure if i understood you correctly but a battery with a closed loop *does* represent a steady state, disregarding the moment when the switch gets closed.
So yes, finally after 30 pages of nonsense with transmission lines which only applied to that switch state transition time, lets now talk how energy is transferred in the steady state, i am all ears 

[EEVblog]

Nice explanation, sounds pretty solid to me. Quantum probability theory trumping Poynting?

It was rather offhand and not really rigorous and didn't really address the actual question (1m/c or 1 second).  The presentation started to discuss the nature of fields, but then seemed more to only address the earlier part of Derek's video. Perhaps that was the intent.

The switch question is secondary to the purpose of the video which was to show the "misconception" that energy flows in the field around the wire instead of within the wire. That is the fundamental question. To me the switch question is a different discussion entirely, and probably a detriment to the fundamental question the video proposes. The question is one fundamentally of fields.
This is why I think any discussion about fundamentals of the "misconception" video should be discussed at DC steady state. Or at the very least, 50/60Hz mains.

[bdunham7]

To me the switch question is a different discussion entirely, and probably a detriment to the fundamental question the video proposes....
This is why I think any discussion about fundamentals of the "misconception" video should be discussed at DC steady state. Or at the very least, 50/60Hz mains.

OK, I'm entirely with you there, the 1m/c trick question is really a non-sequitur.  I think that was also part of my original knee-jerk criticism on the first page of this thread. 

[SiliconWizard]

The switch question is secondary to the purpose of the video which was to show the "misconception" that energy flows in the field around the wire instead of within the wire.

Well, you're right. But that's the fundamental issue with this video. The transient phase is the only way he's found to illustrate the point.

That is the fundamental question. To me the switch question is a different discussion entirely, and probably a detriment to the fundamental question the video proposes. The question is one fundamentally of fields.

Sure, but the video started it. That's what the video proposes. And I agree it is detrimental to the point made in the *title* of the video.

This is why I think any discussion about fundamentals of the "misconception" video should be discussed at DC steady state. Or at the very least, 50/60Hz mains.

At DC steady state only would be really good actually. But unfortunately, I don't think the video addressed that properly. Which leads me to ask: what kind of illustration, and from there, experiment, could you devise to prove the fundamental question, *at DC steady state*? It looks much trickier.

[EEVblog]

The switch question is secondary to the purpose of the video which was to show the "misconception" that energy flows in the field around the wire instead of within the wire.

Well, you're right. But that's the fundamental issue with this video. The transient phase is the only way he's found to illustrate the point.

That is the fundamental question. To me the switch question is a different discussion entirely, and probably a detriment to the fundamental question the video proposes. The question is one fundamentally of fields.

Sure, but the video started it. That's what the video proposes. And I agree it is detrimental to the point made in the *title* of the video.

This is why I think any discussion about fundamentals of the "misconception" video should be discussed at DC steady state. Or at the very least, 50/60Hz mains.

At DC steady state only would be really good actually. But unfortunately, I don't think the video addressed that properly. Which leads me to ask: what kind of illustration, and from there, experiment, could you devise to prove the fundamental question, *at DC steady state*? It looks much trickier.

Yep, totally agree on those points. I don't think the question added value to the title proposal.
Currently chatting with Derek about it and this is my latest reply to him:

"But once again for me it comes down to the DC question (and also low frequency AC like 50/60Hz power transmission). Does the energy *actually* flow in the field or not. My engineer mind is vastly more at ease with the quantum field theory and it's implication at DC and LF. I'd only take power flowing in the field (and hence dielectrics like PCB material and coax cable material) at really high frequencies. It just doesn't "feel right" that the energy is flowing in the field at DC."

and

"I think when it comes to the switch question, the circuit parasitics come into play in the first instances. The capacitance beteen the wires, transmission line theory, antenna theory, coupled transformer theory, and any other engineering viewpoint you want to throw at it. This is why the experimental result is going to match the the results predicted by these engineering methods and models.
I think the problem is that your video has actually generated two different debates. A more practical engineering level one, and a more theoretical physics debate. I now think it's possibly a mistake to try and mix the two, and answer the physics question with the engineering results.
Ultimately they both have to reconcile at some point of course, but the semantics matter."

[EEVblog]

At DC steady state only would be really good actually. But unfortunately, I don't think the video addressed that properly. Which leads me to ask: what kind of illustration, and from there, experiment, could you devise to prove the fundamental question, *at DC steady state*? It looks much trickier.

I'm not sure there is? 
If there was, I think that would be good experimental evidence for quantum field theory?

[bdunham7]

But once again for me it comes down to the DC question (and also low frequency AC like 50/60Hz power transmission). Does the energy *actually* flow in the field or not. My engineer mind is vastly more at ease with the quantum field theory and it's implication at DC and LF. I'd only take power flowing in the field (and hence dielectrics like PCB material and coax cable material) at really high frequencies. It just doesn't "feel right" that the energy is flowing in the field at DC."

So if I have a long, slow transmission line--like a really effective delay line--I can put a pulse of energy in and then I can understand that the energy is in that pulse, a wave travelling through the transmission line, although charges are still moving.  Same if a pulse is radiated through an EM wave, you can understand that the energy is travelling through space, in the form of a wave/photon.  But in those cases you have changing fields and you can point to the energy as it moves and say "there it is!" at each point in it's travels.  In the DC case, I don't see how you can say that as the only thing moving are the charges--the fields are static and conservative.  And for the LF case like power distribution, perhaps it is a blend, but the question is which model dominates?  Can you point to the 'energy' and say "there it is!" at each point in time?  I think you absolutely can--and you'll be pointing at the charges. The fact that you can calculate an S-field and Poynting's Theorem still works out mathematically does not persuade me of anything in particular here. 

[bdunham7]

So here's a thought experiment.  I'm going to invent some tools called 'Millikan tongs' that allow me to grasp and hold a single electron and move it around.  They are weightless and perfectly insulated, so the only effort I need to exert is the work required to move the electron from one point to another. 

What I'm going to do is take the DC power circuit and separate the electric field from the conduction of the charges.  I have a large ground plane, then another plane 1 meter above it.  I then have a battery (the source) that charges the upper plane to -1V relative to ground, which means there is an electric field of 1V/m between the planes.  I then install a wire with a resistor in the middle (the load)  so that it goes almost all the way up to the upper plane, but not quite, so the circuit is not complete.

Now, if I take my Millikan tongs and pluck an electron from the battery side, right near the top so that it is very near the -1V potential and then move the tongs to the top of the load wire, this will require zero work because I am moving it perpendicularly to the E-field lines--IOW it's potential energy is not changing.  When I get there and release the electron, it will cause a current through the load, releasing a certain amount of energy.  So how much energy and can we point to it as it flows?  In this case, for each electron I do this for, there will be 1eV of energy released into the load.  And each electron has a potential energy in the field of 1eV, so as the electrons are moved by the tongs, I can point to it and say "there it is!--there's my 1eV of energy!"  The E-field itself is static and conservative.  If I use the tongs to pick up an electron from the ground side, I will have to do 1eV work to get it up to the top, but at each stage I can point to it and say "there is xxx amount of energy!".  So in this special case, can we agree that the energy is 'flowing' in the succession of 1eV-potential electrons being carried by the tongs?  It's hard for me to see it any other way.

[EEVblog]

But once again for me it comes down to the DC question (and also low frequency AC like 50/60Hz power transmission). Does the energy *actually* flow in the field or not. My engineer mind is vastly more at ease with the quantum field theory and it's implication at DC and LF. I'd only take power flowing in the field (and hence dielectrics like PCB material and coax cable material) at really high frequencies. It just doesn't "feel right" that the energy is flowing in the field at DC."

So if I have a long, slow transmission line--like a really effective delay line--I can put a pulse of energy in and then I can understand that the energy is in that pulse, a wave travelling through the transmission line, although charges are still moving.  Same if a pulse is radiated through an EM wave, you can understand that the energy is travelling through space, in the form of a wave/photon.  But in those cases you have changing fields and you can point to the energy as it moves and say "there it is!" at each point in it's travels.  In the DC case, I don't see how you can say that as the only thing moving are the charges--the fields are static and conservative.  And for the LF case like power distribution, perhaps it is a blend, but the question is which model dominates?  Can you point to the 'energy' and say "there it is!" at each point in time?  I think you absolutely can--and you'll be pointing at the charges. The fact that you can calculate an S-field and Poynting's Theorem still works out mathematically does not persuade me of anything in particular here.

Same here, I have not heard a compelling case of Poynting at DC that makes me think in any way that it's useful.

[Sredni]

I have not heard a compelling case of Poynting at DC that makes me think in any way that it's useful.

Take your pick:

Ian M. Sefton
Understanding Electricity and Circuits: What the Text Books Don’t Tell You
(School of Physics, The University of Sydney)
Science Teachers’ Workshop 2002

Mark Heald

    Electric fields and charges in elementary circuits
    American Journal of Physics, 52 (6), June 1984

    Energy Flow in Circuits with Faraday EMF
    American Journal of Physics, 56 (6), June 1988

Manoj K. Harbola
Energy flow from a battery to other circuit elements: Role of surface charges
2010 American Association of Physics Teachers.
DOI: 10.1119/1.3456567

Igal Galilia and Elisabetta Goihbarg
Energy transfer in electrical circuits: A qualitative account
Am. J. Phys. 73 (2), February 2005
DOI: 10.1119/1.1819932

John D. Jackson
Surface charges on circuit wires and resistors play three different roles
American Journal of Physics 64 (7), July 1996

Noah A. Morris, Daniel F. Styery
Visualizing Poynting vector energy flow in electric circuits
American Journal of Physics 80 (6) June 2012, pages 552-554


Let's not forget Sommerfeld:

Sommerfeld
Lectures on Theoretical Physics (6 Volumes)
Academic Press
the third volume about Electrodynamics
p. 125, Detailed treatment of the field of a straight wire and a coil
There you will find an exercise about an infinitely long resistive wire. Back in 1942 the role of surface charge and the direction of Poynting vector for a DC circuits was no mystery at all. Keep in mind that Sommerfeld is considering a very long resistor, but I copy here the conclusion:

https://i.postimg.cc/pV3mnZKp/screenshot-12.png

Or, if you want to fly a bit lower, Kraus

John D. Kraus
Electromagnetics 2e
section 10.20 Circuit Applications of the Poynting Vector
p. 416
on p. 418, after considering a circuit with a battery (DC) and a resistors he writes:

"In Fig. 10-19aflow lines of the Poynting vector (power flow lines) are shown. It is evident that the power flow is through the empty space surrounding the circuit, the conductors of the circuit acting as guiding elements. From the circuit point of view we usually think of the power as flowing through the wires but this is an oversimplification and does not represent the actual situation."

[EEVblog]

I have not heard a compelling case of Poynting at DC that makes me think in any way that it's useful.

Take your pick:

*snip*

John D. Kraus
Electromagnetics 2e
section 10.20 Circuit Applications of the Poynting Vector
p. 416
on p. 418, after considering a circuit with a battery (DC) and a resistors he writes:

"In Fig. 10-19aflow lines of the Poynting vector (power flow lines) are shown. It is evident that the power flow is through the empty space surrounding the circuit, the conductors of the circuit acting as guiding elements. From the circuit point of view we usually think of the power as flowing through the wires but this is an oversimplification and does not represent the actual situation."

Nope, still not telling me anything useful, just stating that's a way to look at it.
What can looking at it that way DO FOR ME?

Do you have any comment on how quantum field theory views this? or do you think it's bunk?