Does Kirchhoff's Law Hold? Disagreeing with a Master

[seagreh]

Does bsfeechannel’s thesis hold?



Assumption about the magnetic field:

• complete magnetic field is covered by inner circle (our loop with R1 and R2 covers the ‘sourcing’ solenoid).
• outer circle (= probe leads of voltmeters or scopes are not extending to the end of the universe, collecting all the flux return), no they are more or less in parallel and in proximity of the inner circle (let’s say 10cm outside of the inner circle). And have in mind the probe leads are as well superconductive.
• No significant flux (nor flux return) within the area between both circles!

• What will the voltmeter V1 and V2 show (assuming meters are of same brand & type with exactly same internal resistance/impedance) ?
• Is there as well a ‘Gamma Line’ between inner and outer circle ?
• And IF it is beyond the ‘Gamma Line’ in the area where the Sky is BLUE, how do you explain voltages on outer circle with your version of KVL (the sum of voltages is zero)?
• IF we have to conclude it is not beyond the ‘Gamma Line’, hence still in the area of the “Sky Falling”, we need to conclude measurements of both instruments gets influenced by induced EMF as well ?

So far I am not asking where the real seat of EMF actually is 

[Berni]

I don't see why you would need current to shield a static electric field.

...My point is that the coax shield in this configuration has no effect.

I'm not convinced.  I expect the coax will shield the center conductor from the induced electric field.  So you would measure the same voltage whether the scope was on the left or the right side.

Conductors only null the field inside of them, not outside. Hence why current flow is needed in order to generate a opposing magnetic field to cancel out the original one outside the conductor. The induced non conservative electric field appears everywhere around the magnetic field, no need for the magnetic field to actually intersect the conductor.

To find out you can do a quick experiment to join two channels of a scope with a coax cable, wrap the cable around the solenoid and put power into it. When the shield is continuous from one port of the scope to the other you will get next to no voltage, but if you break the shield by cutting it (Or placing a adapter in the cable that disconnects it but leaves center connected) you should suddenly now see plenty of voltage when power is connected to the solenoid.

Does bsfeechannel’s thesis hold?

I don't quite get it how the inner circuit would influence the two meters on the outside at all. Its not connected at all and the resistances in the inner circuit are too high to cause a significant counter field to be generated. You could just get both voltmeters showing half the EMF.

[Sredni]

This post has been 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

As a gift to the other children, here are some color pictures that illustrate the problem you need to solve to lump the Romer-Lewin circuit


What a Kirchhoffian does not get

The youngest among you could aspire to win the Fields Medal.
BTW, a topologist might not agree but...


What a Flatearther does not get

Yep, the maroon challenge above is about the same level of difficulty a flatearther has to face.

"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.

[Sredni]

calm down children please.....

As for the mod who banned me (which I presume it's you given the timing), let me teach you a lesson in what a moderator should do.
A moderator should protect the discussion, not their fragile ego. Can you point out what granted me a seven day ban, except for the fact that I responded to a silly remark in jest?
If you want respect, show some fucking respect in the first place. I am probably old enough to be your father, so don't you fucking call people you don't know children, especially when they are using their own free time to bring a little bit of knowledge in this forum. If you use that condescending tone, the least you can expect is for people to answer in tone. If you didn't like the tone, you should have not used it in the first place.

If you wanted to make a formal request you should have done so and should have specified what you expect people to do: saying their opponent is right so as to not piss them off? Use flowery language? Avoiding repetitions even if they forget what was shown a few pages back? Deleting the parts that show they're wrong to avoid upsetting them? (Hey, that's an idea! Consider it done.)

I do not see any contribution from you in this discussion (including what should be a moderator's job). Actually, thanks to your incompetence and easily punctured ego, you ended up taking away from it.
You took away, to begin with, the answer I had written and got lost because I was banned (for... pulling your thin-skinned majesty's leg) when I was still editing it.
And you took away any other answer from me (*).

Learn to do your 'job', or leave it to someone who has the skills and attitude to do it.

It takes but one incompetent bloke...


(*) As a side note, this is the second time my time gets wasted here, and I too have rules. 
I guess I'll have to thank you for having put me in leech mode: less effort on my part. I'll enjoy flatland from above, where the inhabitants cannot see, nor hear me.


P.S.
I removed only the technical parts from my previous posts. I left all that remained.

[Simon]

The topic was getting heated and was reported, I in turn was trying to jest in calming things down without upsetting anyone. If you don't like a moderation comment then don't answer in jest as the situation has already been determined to be fragile. With no country showing on your profile i can't even put your response down to language barrier.

I don't care for your respect, all I ask is that the forum is respected, my job is to look after the forum, think of me as you will. Granted I may not always get it right, you can always contact me and I'll be only too happy to listen and explain and happily be convinced to remove a ban.

[Siwastaja]

The topic was getting heated and was reported, I in turn was trying to jest in calming things down without upsetting anyone.

Umm, you know, when things get heated, a certain number of people always abuse the "report to moderator" button. It's their way of dealing with the emotions.

You don't need to react to each and every report. You are supposed to see for yourself. You are not obliged to ban people (or react whatsoever) just because you are seeing reports. You are supposed to ban people if they really disregard the actual rules severely enough. You are supposed to be the objective "third party". This shouldn't be a voting system. IMHO.

I have seen your decision making is clearly being affected by the reports, and in my opinion this is an actual problem.

[ogden]

I am probably old enough to be your father, so don't you fucking call people you don't know children

Seems, you have issues. Don't act like kid if you don't like to be labelled as such. By deleting your posts you did not act like a man at all. Attitude you show now is disgusting.

[Simon]

Indeed i do not react to every report and sometimes even email the reporter back and tell them to "suck it up". I looked at the current page of the report and the one before and noted that things were getting a little "heated" with no particular person to blame although one had been by virtue of the report and i was not prepared to blame them so I tried to diffuse the situation.

[Simon]

I am probably old enough to be your father, so don't you fucking call people you don't know children

Seems, you have issues. Don't act like kid if you don't like to be labelled as such. By deleting your posts you did not act like a man at all. Attitude you show now is disgusting.

I have had to "deal" with many a member who is older than me, well old enough to be my father. Age makes no difference on here, we are all the same but in intellect!

[ogden]

Umm, you know, when things get heated, a certain number of people always abuse the "report to moderator" button. It's their way of dealing with the emotions.

While ago I did hurt feelings of Sredni. Somebody called moderator who just said "calm down kids children". I am not 100% sure, but I think one who pressed button was Sredni. It just unexpectedly backfired after he insulted moderator.

Upon return from ban he literally destroyed most of his posts in this thread like little children do when upset. Seems like Simon was right

[Simon]

i can't remember who made the report and I don't care.

[bsfeechannel]

As for the mod who banned me (which I presume it's you given the timing), let me teach you a lesson in what a moderator should do. A moderator should protect the discussion, not their fragile ego. Can you point out what granted me a seven day ban, except for the fact that I responded to a silly remark in jest?

I can understand that you are pissed off because of all of the hours spent in front of the computer, trying to convey the most scientifically precise and consistent replies. I'm shocked to know that you were banned temporarily.

However we need to express our appreciation for Simon's work. I've been a moderator before. It is one of the most ungrateful tasks, let me tell you.

P.S.
I removed only the technical parts from my previous posts. I left all that remained.

Please reconsider your decision. Your posts are one of the reasons that I reckon this one of the best threads of the forum. Think of all other people who will read this thread and get educated on the subject we've been discussing.

[EEVblog]

I think you nailed it. Getting stuck to his (in)famous experiment and trying to criticize, explain, praise or debunk it, as many of us have done one way or another, turns out completely pointless.
You're right, it's about fundamental physics, and whereas I still think the experiment itself is flawed, and has led some of us to misinterpret his point at first, he probably couldn't care less.

I still think he's caused enough confusion to many - you just need to look at this endless thread - that his approach is pedagogically flawed. As I noted much earlier, his written courses are actually much clearer than the drama he tends to make with his oral lectures - at least IMO. But I know you have to keep your students attentive. Or at least "entertained"...
The good point is that this has raised a series of interesting questioning. And after all, if this was his intention, that's well done.

At first, that's what I thought. Lewin was right but messed things up when trying to explain it. However after, what?, three or four months discussing about the subject, reading and re-reading papers, books, analyzing the videos, etc., and even performing experiments in my lab, I came to conclusion that the one who nailed it was exactly Lewin.
He touched on highly sensitive taboo, or myth, that is the validity of Kirchhoff's laws. Those who bash him are exactly those who consider RF, or anything Maxwell related, black magic.
I, and others, on this thread managed to realize not only how removed from understanding the basic tenet of electronics many involved with it are, but how recalcitrant they are to even try to. And this is alarming.

Yes, engineers are inherently recalcitrant, they usually need to be because electronics engineering is more of an applied practical science than a theoretical science. Most practical practicing engineers rarely dive into the deeply theoretical world, they just use practical tools like Kirchhoff's to get the job done.
What would Bob Pease do...

[EEVblog]

P.S.
I removed only the technical parts from my previous posts. I left all that remained.

What does that mean exactly?
Did you remove all technical content form all your previous posts?
What is your intention for future posts?

EDIT: I see you have gone through and edited a lot of your previous posts to the same thing. This is borderline spam.

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):


Kip
Fundamentals of Electricity and Magnetism 2nd ed

Lorrain, Courson
Electromagnetic Fields and Waves 2nd ed

John Kraus
Electromagnetism 2nd to 4th ed

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

Panofsky, Phillips
Classical Electricity and Magnetism 2nd ed

Bleaney
Electricity and Magnetism 3rd ed

Nayfeh, Brussel
Electricity and Magnetism

[bsfeechannel]

Yes, engineers are inherently recalcitrant, they usually need to be because electronics engineering is more of an applied practical science than a theoretical science. Most practical practicing engineers rarely dive into the deeply theoretical world, they just use practical tools like Kirchhoff's to get the job done.

Many on this forum and I are engineers who are not recalcitrant to learn when it is shown that a certain concept is wrong. Sticking to pseudo-scientific claims has nothing to do with being practical.

We proved that Mehdi's claims are bullshit and there is no justification in any exercise of any practice that can reverse that fact.

If not knowing theory was a sign of good or practical engineering, you should be discouraged to learn Kirchhoff's laws themselves. They are no less "theoretical" than Maxwell's equations. In fact, Kirchhoff's laws ARE Maxwell's equations for special cases.

This equation: N = V^pk_p/(2πB_satA) is a solution of Faraday's equation and that's what we use to calculate the dimensions and number of turns of the primary of any transformer with EI, CI, toroidal, etc, ferromagnetic cores. It is a practical equation. You must have transformers by the hundreds in your lab and your house. It is a circuital law where KVL is invalid. I.e., if KVL held in this case, you would never have a transformer.

So, ignoring Maxwell's equations has nothing to do with being practical. It is just an incapacitating feature. Deciding whether it is worthwhile learning them is a matter of choice.

What would Bob Pease do...

I pretty much think that he would not confuse practicality with ignorance. He was the Czar of Bandgaps. I would kill to have 10% of his knowledge.

[EEVblog]

So, ignoring Maxwell's equations has nothing to do with being practical. It is just an incapacitating feature. Deciding whether it is worthwhile learning them is a matter of choice.

I think you are taking this a bit too seriously. No one (at least not me) is talking about being deliberately ignorant, or that being ignorant of the deep theory is a good thing.
Just pointing out that most practical engineers need not concern themselves with Maxwells equations (esp in a case like this) and this whole debate is all but pointless to any practical engineer. They'll just happily continue to use Kirchhoff's to make practical stuff that works, and just go "meh" to Lewin's academic argument (in this case). And there's nothing wrong with doing that, horses for courses.

I have not followed this whole thread, so I don't know about your arguments that Electroboom's claims are 100% bullshit, but I suspect that this isn't such a black and white case.
I don't think anyone doubts that Lewin is ultimately right (he is), but AFAIK he failed to address any of Electroboom's practical points.
From what I have seen, it's Lewin with his fingers in his ears repeating "KVL doesn't hold" 100 times, vs Electroboom trying to methodically evaluate the problem from a practical demonstration standpoint. From that I know who I have more respect for at the very least.

[Berni]

The half the whole tread is mostly just about being overly picky about the details and naming of things in physics. The thread did provide some interesting thought experiments along the way, but untimely things never got any closer to an agreement.

Circuit analysis (And that includes KVL) was never meant to be used to explain the underlying physics, but instead doing the opposite, made to abstract away any non vital parts of physics to let you focus on the operation of a circuit. If you apply circuit analysis the wrong way to your circuit then you get wrong results. Garbage in garbage out simple as that.

So if KVL is for the birds then the entirety of circuit analysis theory is for the bids as well. I'm sure any proper electronics engineer will disagree because circuit analysis has served them well ever since learning it in school.

So please circuit analysis for explaining circuits and not physics.

I also don't understand what Sredni was trying to accomplish by deleting content from his posts. Basically vandalizing his own work to make it harder for someone else to follow the tread.

[bsfeechannel]

Just pointing out that most practical engineers need not concern themselves with Maxwells equations (esp in a case like this) and this whole debate is all but pointless to any practical engineer. They'll just happily continue to use Kirchhoff's to make practical stuff that works, and just go "meh" to Lewin's academic argument (in this case). And there's nothing wrong with doing that, horses for courses.

I am a practical engineer, and this is discussion is not pointless at all. Lewin's experiment is only a "meh" experiment for the inattentive viewer (as I was one day).

I have not followed this whole thread, so I don't know about your arguments that Electroboom's claims are 100% bullshit, but I suspect that this isn't such a black and white case.

I regret to inform you that Mehdi's claim that Kirchhoff always holds is 100% bullshit. This thread is long, but is awesome. I spent a lot of time that I didn't and I don't have with it, but it was worth every second.

I don't think anyone doubts that Lewin is ultimately right (he is), but AFAIK he failed to address any of Electroboom's practical points.

Our investigation on the subject showed that Lewin addressed his practical points. But Mehdi denied them one by one.

From what I have seen, it's Lewin with his fingers in his ears repeating "KVL doesn't hold" 100 times, vs Electroboom trying to methodically evaluate the problem from a practical demonstration standpoint. From that I know who I have more respect for at the very least.

Mehdi made you believe that. But we are not buying it. We're not so gullible. This is just one example. His video is full of facepalm moments.

Richard Feynman, recommended by Mehdi, said:

The difference of these two potentials is what we call the voltage difference, or simply the voltage V, so we have

V = −∫_b^aE⋅ds = −∮E⋅ds.

In his second video, "Kirchhoff's Voltage Law vs Faraday's Voltage Law" @ 8:07, he says:

But then you might say that the voltage is integral of E dl [i.e −∮E⋅ds] . Well, that's not true. Voltage is any energy per unit charge. Not just energy from electric sources. Hmm. Is that it? Does Dr. Lewin believe that voltage is only defined by electric forces?

You clearly see that Mehdi not only denies the definition of voltage given by Richard Feynman and repeated by Lewin, but also doesn't understand what the integral means. And he has the petulance of throwing his misunderstanding upon Lewin's shoulders.

After that he draws every kind of stupid conclusion with his experiments because of course he refuses to understand the phenomenon.

However, if his refractory attitude to understanding (a.k.a stupidity) is not enough, he ends his video saying that he read Feynman's reference above (@13:16) and @13:58 he says

So Dr. Belcher also concluded that Dr. Feynman himself and I have the same definition for voltage [...]

Now you can see that he's an outright liar.

People like that do not deserve our respect and should not be addressed as engineers.

And you can see how dimwitted Mehdi's audience is for not noticing this.

EDIT: Wrong reference to Mehdi's video corrected.

[beanflying]

....

You continue to think being an arrogant intellectual bully who time and again resorted to petty name calling and demeaning anyone not totally agreeing with you is a credible Scientific or Engineering method. On any level and as I mentioned a long while ago would not be tolerated in most workplaces or institutions of learning.

In this thread is some great reading but so much useless non Science and Engineering and OTT Ego driven non debate.

Play the science and engineering not play the man!

[bsfeechannel]

The half the whole tread is mostly just about being overly picky about the details and naming of things in physics. The thread did provide some interesting thought experiments along the way, but untimely things never got any closer to an agreement.

This thread was never about coming to an agreement.

Does Kirchhof hold or not? Under varying magnetic fields, definitely not. Period. Never held. Never will.

You can disagree until the cows come home. The truth is established and that's what counts.

Engineers do not design their projects upon opinions, but upon established truths.

Circuit analysis (And that includes KVL) was never meant to be used to explain the underlying physics, but instead doing the opposite, made to abstract away any non vital parts of physics to let you focus on the operation of a circuit. If you apply circuit analysis the wrong way to your circuit then you get wrong results. Garbage in garbage out simple as that.

Kirchhoff's laws were meant to explain the underlying physics. Read Kirchhoff's original paper posted by seagreh. If you can't read German, cross the border and kindly ask an Austrian inhabitant to read it for you.

So if KVL is for the birds then the entirety of circuit analysis theory is for the bids as well. I'm sure any proper electronics engineer will disagree because circuit analysis has served them well ever since learning it in school.

Kirchhoff is for the birds means that Kirchhoff is not a fundamental law. Just that. Be prepared to see it being violated repeatedly. It just means that circuit analysis has its limits. It cannot be used for every kind of circuit. And you have to know when it is not applicable.

I bet SPICE didn't tell you that.

So please circuit analysis for explaining circuits and not physics.

Circuit analysis is physics.

I also don't understand what Sredni was trying to accomplish by deleting content from his posts. Basically vandalizing his own work to make it harder for someone else to follow the tread.

I guess he found that this forum was not worthy of his posts. But I guess he has to recognize that talking back to a moderator, in his duty as a moderator, is never a good idea. Even more because Sredni was doing nothing wrong. However his attitude induced to Simon think that he was the cause of the problem and banned him.

In my opinion, Sredni didn't deserve to be banned, but Simon didn't deserve Sredni's rant either.

[EEVblog]

I also don't understand what Sredni was trying to accomplish by deleting content from his posts. Basically vandalizing his own work to make it harder for someone else to follow the tread.

Yep, I don't get it either, all that hard work gone, but we've seen this before on the forum and it usually doesn't end well unfortunately. I hope that doesn't end up being the case here.

[bsfeechannel]

....

You continue to think being an arrogant intellectual bully who time and again resorted to petty name calling and demeaning anyone not totally agreeing with you is a credible Scientific or Engineering method. On any level and as I mentioned a long while ago would not be tolerated in most workplaces or institutions of learning.

In this thread is some great reading but so much useless non Science and Engineering and OTT Ego driven non debate.

Play the science and engineering not play the man!

Wait a minute! Dave can say that he didn't follow the thread and that he doesn't respect Lewin based on mere impressions. I discussed the theme exhaustively, concluded, not decided, that Lewin deserves our respect and Mehdi doesn't and I am an arrogant intellectual bully?

Is that because I cared to study, read, read again, check, double check, watch Mehdi's videos more times than any of his own subscribes,  watch Lewins videos the same number of times, just to ascertain the truth? Just because I don't want to forward misconceptions?

Am I a bad guy?

[Siwastaja]

Is that because I cared to study, read, read again, check, double check, watch Mehdi's videos more times than any of his own subscribes,  watch Lewins videos the same number of times, just to ascertain the truth? Just because I don't want to forward misconceptions?

No, not at all. At least I hugely respect your work on studying, checking, and explaining; I believe others respect it as well.

All the namecalling (like the flat-earther shit), roasting inbetween is what people don't like. It's called "bullying". But I think you have been getting better during the thread. Try to keep on the subject, try to be less condescending, and you'll do fine. You are not superior. If you feel like others are really dumb, you are often not seeing something.

Social constructs can be difficult sometimes.

[Simon]

If you feel like others are really dumb, you are often not seeing something.

Social constructs can be difficult sometimes.

Depends, 2 minutes ago I interrupted a conversation between my manager and a colleague to point out that they are trying to talk about how to put holes in metal work for wiring before we have even agreed the wiring (that i will have to design). Am I superior? yes I am! The world is full of dumb people that call themselves engineers because they do drawings. Doing drawings and designing are two entirely different things.

[beanflying]

Wait a minute! Dave can say that he didn't follow the thread and that he doesn't respect Lewin based on mere impressions. I discussed the theme exhaustively, concluded, not decided, that Lewin deserves our respect and Mehdi doesn't and I am an arrogant intellectual bully?

Is that because I cared to study, read, read again, check, double check, watch Mehdi's videos more times than any of his own subscribes,  watch Lewins videos the same number of times, just to ascertain the truth? Just because I don't want to forward misconceptions?

Am I a bad guy?

For someone with intelligence you are WRONG to believe aggression and name calling adds to any debate, stick to the Science and Engineering.

Even Lewin managed to apologize for an earlier video retort to Mehdi and if this socially flawed human can manage that there may be hope for you too.