Does Kirchhoff's Law Hold? Disagreeing with a Master

[Sredni]

It's Groundhog Day.
Again!

<sigh>

EDIT

This post has been shortened and cleansed to avoid upsetting other children.
Whatever was written here can be found in one or more of the following books (in no particular order, and without mentioning the usual suspects Feynman, Purcell, Griffiths, Ohanian, Jackson):

Panofsky, Phillips
Classical Electricity and Magnetism 2nd ed

John Kraus
Electromagnetism 2nd to 4th ed

Ramo, Whinnery, VanDuzer
Fields and Waves in Communication Electronics 2nd or 3rd ed

Bleaney
Electricity and Magnetism 3rd ed

Nayfeh, Brussel
Electricity and Magnetism

Kip
Fundamentals of Electricity and Magnetism 2nd ed

Lorrain, Courson
Electromagnetic Fields and Waves 2nd ed

"Books" are static paper based documents that can be found in libraries. They are like smartphones, but (usually) bigger, with lots and lots of extremely thin flexible e-ink screens and a very long battery life. Libraries are...
Oh, never mind. Keep on pushing that square peg into that round hole. With a big enough hammer, it will fit.

[bsfeechannel]

It's Groundhog Day.
Again!

Now I understand when Lewin said that these guys are flat-earthers. People advocating pseudo-scientific claims in electronics is the end of our profession.

[rfeecs]

OK, probably way off topic, but I guess I'm losing my mind.  I watched this video.  What the hell?  Could something on the internet not be right?  Or am I confused?  How could this guy get the fields so wrong?  He doesn't even agree with Wikipedia.  So I can't believe everything on the internet? :

Yikes.  "We have a strong electric field inside the wire":

https://youtu.be/C7tQJ42nGno

Comments are overwelmingly positive "mind blown"!

[Berni]

Yes there are infinitely many paths trough air to close a 1/4 turn around a transformer. But for circuit analysis its most convenient to define that path as being a path with zero EMF, this is so that the component is properly lumped so that all of the field effects happen inside the component. This brings the EMF over a section of wire to a single well defined number.

And if you are after the circuit analysis perspective of voltage at every point in Dr. Lewins circuit here it is (Tho R1=R2 in here because it makes the diagram clearer):

(Taken from https://www.eevblog.com/forum/chat/does-kirchhoffs-law-hold-disagreeing-with-a-master/msg2085523/#msg2085523 )

Notice that there are no sudden 1V jumps anywhere.

Circuit analysis abstracts magnetic effects down to just U_L=L*di/dt on inductors. And this is what you would get if you had thousands of series inductors forming the way around the loop, you get a tiny voltage on each one that slowly and gradually adds up as you go around.

Close each one of those inductors with a wire that travels 90 degrees to the induced electric field at all times and you get the voltages in this diagram. And thats how you get 250mV across a 1/4 turn. You can measure it in Dr. Lewins circuit with a voltmeter. Go ahed and try it if you don't believe me.

OK, probably way off topic, but I guess I'm losing my mind.  I watched this video.  What the hell?  Could something on the internet not be right?  Or am I confused?  How could this guy get the fields so wrong?  He doesn't even agree with Wikipedia.  So I can't believe everything on the internet? :

Yikes.  "We have a strong electric field inside the wire":

Comments are overwelmingly positive "mind blown"!

Yeah maybe he doesn't get all of it right, but the Poynting vector thing is pretty interesting as i haven't seen it before.

[bsfeechannel]

OK, probably way off topic, but I guess I'm losing my mind.  I watched this video.  What the hell?  Could something on the internet not be right?  Or am I confused?  How could this guy get the fields so wrong?  He doesn't even agree with Wikipedia.  So I can't believe everything on the internet? :

Yikes.  "We have a strong electric field inside the wire":

https://youtu.be/C7tQJ42nGno

Comments are overwelmingly positive "mind blown"!

It's on topic.

That's the problem with those "science" and "engineering" channels. If you want to make a career out of Youtube, what matters is views. Views, views, views. Youtube recommends you to publish at least one video a week. It is impossible to produce a science or engineering "report" with all the rigor they deserve every week unless you have a professional team of consultants, experts, proofreaders, etc. And even the channels that do have those professionals and lots of funding produce gross errors sometimes.

I only watch the EEVBlog videos because Dave is honest. In the video EEVBlog #22 (6:39) he said:

I got a rather interesting comment once, in fact I've had more than once in various forms, but the comment was basically: how do we know you're RIGHT? How  can we take your word for it? On, you know, all these things and all these topics? And, well, you know, it's a really good question, and the answer is you SHOULDN'T. You should never take anyone's word for it. Don't take anything i say on these blogs as gospel. Uh, you know, I've been in the industry for 20 years so, you know, I like to think I do know what I'm talking about mostly. But, you know, don't take my word for it. All my blogs, and all the things I talk about on here are designed to be food for thought. You're supposed to use your own engineering judgment and, you know, and go out and verify things. If you're, you know, if you're really interested in something, don't complain that i didn't explain it right or and you know i might have got it a bit wrong or something like that. Go out and investigate for yourself. That's what it's all about: food for thought.

This pretty much uncovers what video blogging is about. However, freed from rigor, the appeal to sensationalism is too tempting for some guys like Mehdi and this guy of the video above. It may stir up debates, but without the proper disclaimers, it helps to propagate all kinds of inconsequential stupid conceptions like we've seen lately.

Which is absolutely detrimental to our métier.

[Sredni]

OK, probably way off topic, but I guess I'm losing my mind.  I watched this video.  What the hell?  Could something on the internet not be right?  Or am I confused?  How could this guy get the fields so wrong?  He doesn't even agree with Wikipedia.  So I can't believe everything on the internet? :

Yikes.  "We have a strong electric field inside the wire"

Oh, it's more on topic than it could seem.
[snip]

one thing I want to say now: I am grateful for Mehdi's ignorance, because it gave me the opportunity to deepen my understanding of how circuits work at a field level)

Comments are overwelmingly positive "mind blown"!

This is one of the dangerous aspects of the social networks. The majority of uneducated and superficial people self-reinforcing their incorrect beliefs. The voting system (like the one about comments) is basically a way to spread ignorance.
(Man, I am starting to think like Anakin in "Attack of the Clones").

[rfeecs]

I don't know where the "We've got a strong electric field inside (the wires)" came from.  But the rest of the picture seems to come from the one reference that he lists for the video, which is the Feynman lectures:
http://www.feynmanlectures.caltech.edu/II_27.html
It's pretty funny Feynman constantly calls this a "crazy" theory, "obviously nuts", etc.

The example Feynman gives is for a piece of resistance wire, where he says the E field is parallel to the surface of the wire.  But I would assume that in the video the wire is a good conductor and the E field would be almost perpendicular to the surface of the wire.

The video, including the animation showing energy flow, gives the impression that energy is radiated out of the battery and into the wire and the light bulb with most of the energy flowing into the wire from the space around it.  A few people in the comments are wondering how electrical circuits can work if the wires are absorbing electromagnetic energy from all around.

Here are a few references that seem to have better simple explanations:
http://sites.huji.ac.il/science/stc/staff_h/Igal/Research%20Articles/Pointing-AJP.pdf
http://www.furryelephant.com/content/electricity/visualizing-electric-current/surface-charges-poynting-vector/
http://www.abc.net.au/science/articles/2014/02/05/3937083.htm

[Sredni]

Pages 26 and 27 of the reference I've mentioned before refer to that passage in Feynman's book.

EDIT:
[snip]

All I want to add that that dude has chosen to stick to his "the E field is STRONGER in the cables" and is also convinced that immediately out of the conductor the E field is parallel to it.
It's "not a mistake". It's an "educational choice".

[ogden]

So, you keep asking what is the voltage across a quarter turn, but you have to tell us where is the varying magnetic field region and along which path among the infinitely many you want to compute that voltage. You might end up with a quarter of a volt but also with much less.

I said "transformer" which means magnetic fields are contained, they do not influence voltmeter leads. I say 1/4 turn will give 1/4 V EMF. Do you agree?

[Sredni]

So, you keep asking what is the voltage across a quarter turn, but you have to tell us where is the varying magnetic field region and along which path among the infinitely many you want to compute that voltage. You might end up with a quarter of a volt but also with much less.

I said "transformer" which means magnetic fields are contained, they do not influence voltmeter leads. I say 1/4 turn will give 1/4 V EMF. Do you agree?

As I said before, you have to specify where the B field region is and where your path is. Post a picture of your quarter of a transformer with a shaded region showing where the B field varies and we'll see if we agree or not. You might discover that while you can have the field contained with a quarter of an arc, you no longer can have it when you consider that arc as part of a circular 'transformer'. Unless you consider a different system, like the one I showed Berni a few pages back.

But please, post the picture, so that we can be sure what we are talking about.

Edit: plurals, it appears I place those at random.

[ogden]

So, you keep asking what is the voltage across a quarter turn, but you have to tell us where is the varying magnetic field region and along which path among the infinitely many you want to compute that voltage. You might end up with a quarter of a volt but also with much less.

I said "transformer" which means magnetic fields are contained, they do not influence voltmeter leads. I say 1/4 turn will give 1/4 V EMF. Do you agree?

As I said before, you have to specify where the B field region is and where your path is. Post a picture of your quarter of a transformer with a shaded region showing where the B field varies and we'll see if we agree or not. You might discover that while you can have the field contained with a quarter of an arc, you no longer can have it when you consider that arc as part of a circular 'transformer'. Unless you consider a different system, like the one I showed Berni a few pages back.

But please, post the picture, so that we can be sure what we are talking about.

Edit: plurals, it appears I place those at random.

So you don't know what magnetically shielded transformer is, I have to show picture?  Do you know what voltmeter is? Or wire?

Shall I show picture of voltmeter and wire as well?

[Sredni]

So you don't know what magnetically shielded transformer is, I have to show picture?

Yes, please. You can draw, can't you?
Maybe, when you draw it you realize where the problem is.
Don't forget that a lumped component is essentially zero dimensional so its terminals are very close together.

[ogden]

So you don't know what magnetically shielded transformer is, I have to show picture?  Do you know what voltmeter is? Or wire?

Shall I show picture of voltmeter and wire as well?

Great news! It appears you can find virtually anything on internet, so you got picture. In following circuit "no magnetic field here" is clearly noted for wires of voltmeter "V2". I say it shall show 1/4V. What do you say?

[Sredni]

Just draw your quarter circle isolated transformer, please.

Or, as Rihanna would put it: "Shut up and draw!"

[ogden]

Just draw your quarter circle isolated transformer, please.

Or, as Rihanna would put it: "Shut up and draw!"

Can't you see picture in my previous post? If you do not understand "magnetic field of transformer do not influence voltmeter leads" and ask for drawing, then you have problem, kid.

[Sredni]

I can see the picture in your previous post and that is not what I asked you to draw. I asked you to draw your "1/4 turn magnetically isolated transformer" highlighting the region of space where the dB/dt happens, so that we can reason on that.

Can't you do it? There is more than a way to do it and you are undecided? Pick one. We'll go from that.

[ogden]

I can see the picture in your previous post and that is not what I asked you to draw. I asked you to draw your "1/4 turn magnetically isolated transformer" highlighting the region of space where the dB/dt happens, so that we can reason on that.

Can't you do it? There is more than a way to do it and you are undecided? Pick one. We'll go from that.

I do not need to. Picture I did show is good enough. Inside two circuit loops there's magnetic field and it is specifically shown where's no magnetic filed, indicated by note "no magnetic field here" (leads of voltmeter "V2") - meaning leads of voltmeter "V2" are not influenced by magnetic field. Do you have problem to understand that circuit or what?

[edit] I repeat question - what will be voltage shown by voltmeter V2?

[Sredni]

Maybe you did not read the last 32 pages, but the whole point of this thread is that there are people like you who believe the Romer-Lewin ring is lumpable, and people like me who believe it isn't. So, no, I do not see a magnetically isolated transformer there (for one, where do the magnetic field lines return?, the way it is drawn they return at infinity), much less a quarter turn magnetically isolated transformer. So please, put words aside and produce a picture of your quarter turn magnetically isolated (and as such lumped) transformer.

EDIT: added boldface to highlight the part that should make it clear that the field is NOT contained.

[ogden]

Maybe you did not read the last 32 pages but the whole point of this thread is that there are people like you who believe the Romer-Lewin ring is lumpable, and people like me who believe it isn't.

I did not say my transformer is like "Romer-Lewin ring". In case I did - please quote me. I did say "magnetic fields are contained". Seems, you have problem to comprehend what it means.

I said "transformer" which means magnetic fields are contained, they do not influence voltmeter leads. I say 1/4 turn will give 1/4 V EMF. Do you agree?

For one who understands Maxwell's equations, It shall be easy to answer w/o requesting picture, oil painting or youtube video.

[edit] Transformer core which does contain magnetic field:

https://www.eevblog.com/forum/chat/does-kirchhoffs-law-hold-disagreeing-with-a-master/msg1972940/#msg1972940

[ogden]

where do the magnetic field lines return?, the way it is drawn they return at infinity

It is said - they are contained 

[ogden]

EDIT: added boldface to highlight the part that should make it clear that the field is NOT contained.

Most ridiculous debate imaginable. I said that magnetic field is contained, your argument is "should make it clear that the field is NOT contained".

              

[edit] BTW You did not answer the question about indication of "voltmeter V2"

[bsfeechannel]

[edit] I repeat question - what will be voltage shown by voltmeter V2?

You can easily detect that someone's claim is based on pseudo-scientific assumptions when it leads to contradictions. You say the voltage that the voltmeter will show is 250mV, but Mabilde and Mehdi, two other kirchhoffools like you, measured 0V (Mehdi's fist video @6:42 and Mabilde @21:55). Of course, they came with stupid explanations as to why the voltage they measured didn't match their expectations, while Faraday's law was predicting exactly what they measured.

Kirchhoffools' claims are so flawed that they can't even agree with each other. Pathetic.

[ogden]

You say the voltage that the voltmeter will show is 250mV, but Mabilde and Mehdi, two other kirchhoffools like you, measured 0V (Mehdi's fist video @6:42 and Mabilde @21:55). Of course, they came with stupid explanations as to why the voltage they measured didn't match their expectations, while Faraday's law was predicting exactly what they measured.

Kirchhoffools' claims are so flawed that they can't even agree with each other. Pathetic.

Don't be mad that I am using your mistake as an argument   Mehi's video @6:42 do not measure 0V but as he say 1/10 of the voltage measured before - because as he says "current of the loop is the same, resistance is 1/10".

[edit] In case you did not notice, we don't talk about Kirchoff's rules at all, yet you manage to mention them, insulting way. THAT's pathetic

[Sredni]

Most ridiculous debate imaginable. I said that magnetic field is contained, your argument is "should make it clear that the field is NOT contained".

The fact that you say the field is contained does not mean that it is contained.
You have to contain all the lines of the magnetic field. Like in a toroidal transformer, or an M or EI transformer. In this case the field is generated by an infinitely long solenoid, and the field lines are not contained. As a matter of fact they close at infinity and the whole universe is in the middle.

The fact that you do not see it does not make it less true.

[edit] BTW You did not answer the question about indication of "voltmeter V2"

In the Romer-Lewin circuit? (BTW, maybe you meant v6) It's the value shown by bsfeechannel: 0V if the conductor is perfect, otherwise it's the drop in the copper for the current flowing in the circuit. A few tens microvolts, maybe, depending on the geometry and dimensions of the conductor. But we can say it's zero, if there is no leakage of magnetic flux (something that is hard to realize in practice with small primary coils).

edit hundreds to tens, anyway we can easily compute it

[bsfeechannel]

Don't be mad that I am using your mistake as an argument

I'm not mad, why would I be?

Theory and experiment confirm what's in the drawing.

I only pity you for being so hardheaded.

  Mehi's video @6:42 do not measure 0V

Oh yes he does. I'm referring to the original video, the one Dave posted.

[edit] In case you did not notice, we don't talk about Kirchoff's rules at all, yet you manage to mention them, insulting way. THAT's pathetic

I always forget that you own the thread. My sincere apologies.