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Author Topic: Professor Walter Lewin's Non-conservative Fields Experiment  (Read 252422 times)
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Harvey,

I'm sorry that you take me as being disingenuous. I'm mainly interested in technical discussions and understanding the point of view of others regarding this experiment. I believe I have a good grasp of this experiment and I do not yet buy into the assertion that professor Lewin et al are promoting, but I am also trying to understand why others see something different than I do.

I have difficulty understanding what people write sometimes, which is why I have been asking you for clarification, that is all. It seems to be upsetting or frustrating you though, so I'll simply refrain from discussions on this topic with you, until perhaps a later date.

As it seems no one else is really interested in this discussion, I guess it may be quiet here for a while.

Cheers,
Darren

Here is the thing Darren, you're smart and your aptitude is evident in your posts - so when you claim to be confused after repeated diverse explanations it comes across quite disingenuous or even insulting. Not that I'm offended in any way, its only that such tedious process of regurgitating the same things over and over in different textures gets wearisome and nonproductive - especially when they are focused on contextual semantics. I think the word I see thrown around all the time on the forums is 'pedantic'  :P. What comes across to me, and other readers is that you just want to be right about this on some level even if its to argue that one divided by two cannot possibly be one half because the professor shows it to be different. Apart from that, I rather like you - you have skills with the Sims that puts many of us to shame. And you have a root fundamental understanding of things that is beneficial in workable ways.

Here is the crux of it: KCL and KVL cannot be applied in a changing scenario. No matter how hard you try, you must extrapolate in between your time slices because each time slice must equal zero for the loop. That is not reality.

So, as is stated in many places, Kirchhoff's Law is only a special case of Faraday's law where the closed loop integral equals zero. The only place this happens is in a conservative field aka static. Therefore, Kirchhoff's Law should not be used or manipulated into use where non-conservative fields are in play.

This matter really isn't of much importance in simulations where we have time to manipulate things to get the desired results. But it becomes very important as we get deeper into the physics of how substrates and conductors interact with changing fields at near quantum levels. The professor recognized that it was unfair to teach our students that it was a certain way when reality is different because it was just setting them up for the big "Why did that happen?" when they first experience it in the real world.

The most valuable thing I took away from that lecture was that changing magnetic fields are non-conservative - ergo, energy can be extracted from them. IMHO, that is way more important than "the wires are inductors". The second most important thing is that non-conservative fields are path dependent and time variant - so it matters both 'when' and 'where' you take you measurements regardless of how the energy got in the circuit.

Kirchhoff's Law is all about path and time independence and that is why it is generally a bad idea to try and use it to evaluate the experiment outlined in this thread. But hey, I've used a butter knife as a screwdriver in a pinch so I'm sure we can get it to work if we tweak it just right. ;)

Cheers,

Harvey
   

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Harvey,

I'm starting to think about something Lewin said. Something about 'you'll never see this again'.

I think what he meant is you will see this constantly throughout your career but not as well detailed or clearly placed in front of you. I think it is a warning to avoid the pitfalls of having to rely on an adjusted rule vs. a real understanding of what happens.

My work is filled with this. I'm supposed to identify a root cause because the previous root cause found proved incorrect and the wrong solution was applied. There was nothing wrong with the previous result. The problem was always the method or the understanding of what transpired. So the wrong fix is applied.

Some of the arguments I get about how wrong I am are amazing. In the end the correct solution is always clear when the answer is correct. Not so with this example, for many.


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@wavewatcher
I was going to edit my post as well just after I wrote it, We all know where that kind of critical debate leads, usually nowhere, and I apologise if I was out of line, which I was -- again :D. That was my somewhat twisted way of actually agreeing with you that I do not think KVL can apply here and I believed you were implying we should not have to mangle the law to make it fit where it cannot which I agree with. I would also agree that I went a little overboard when responding to your statement that zero potential is BS. I feel very strongly about this issue because I have spent a great deal of time in research and experiments to get to the point that I can nail down where and why this phenomena occurs. I will try to explain my point of view a little more rationally next time.

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I think what he meant is you will see this constantly throughout your career but not as well detailed or clearly placed in front of you. I think it is a warning to avoid the pitfalls of having to rely on an adjusted rule vs. a real understanding of what happens.
My work is filled with this. I'm supposed to identify a root cause because the previous root cause found proved incorrect and the wrong solution was applied. There was nothing wrong with the previous result. The problem was always the method or the understanding of what transpired. So the wrong fix is applied.
I would agree completely, I am in the process of finishing a new measuring instrument which will show exactly what is happening in the Prof Lewis circuit, where it is happening and why it is happening to hopefully clear this up once and for all. I think we need to clarify as many loose ends in as much detail as we can if we are ever going to progress and from what I have seen so far in my testing of this circuit leads me to believe that the effect misleading many people applies to a great deal of other circuits which do not do what we expect.
Regards
AC



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AC,

I can't say that zero potential doesn't exist at all. That question might be a little too deep for me right now with other 'life' going on.

What I do believe is it would be difficult to find a point or level that appears as zero from all perspectives. What I was referring to was zero on a scope or meter in even the more strange setups.

The zero I speak of would better be described as a reference point. 'Bird on a wire' kinda stuff. The ground we walk on is considered zero but it has a charge with respect to everything else in our normal life. While I normally avoid mentioning subatomic particles and don't care to know much more about them, 'neutral' is the closest thing to zero charge I can think of.

'Neutral' is a better word. Basically meaning it is no charge with respect to something else.

I'll admit my attempt to open other minds to the understanding of problems possible with massaging a perfectly good law for the purpose of getting the 'right' answer was stretching it. It is important that folks understand this stuff.

Just believing Lewin's example requires understanding that time and path are core components AND the need for these components to make things like induction, phase relationships and so much else work and understandable.

It torks me off when I speak to folks from our IT department about implementing some well known function. The poor people are highly trained and very smart. The problem is... they have no idea how a computer really works. When you mention 'assembly' to get something done they think you are talking about what must be done after Santa arrives and before the kids wake up.

I had one argue about a related issue until I finally told him he was right. Then I had time to do it myself. I use it on a local server but IT refuses to implement it enterprise wide. They can't understand the source code and are afraid of what might be in it  :(

Every discipline needs to avoid short-cutting themselves to the point - where they think what was published a relatively short time ago - is gospel or completely correct. I don't care what the rule is. There is a good chance it isn't complete, is not one-size-fits-all, has been translated to death or just plain wrong.

When you look at occasions where Faraday trumps Kirchhoff, Maxwell contradicts relativity, Maxwell can't work without throwing in a little Lorentz, Faraday looses and Lorentz takes over, Lenz misses one, physic's use of 'covariance' and 'imaginary' (I could go on).... Is there any wonder I don't trust any law unless it passes on my bench?

I still want to perform Lewin's example. Not because I doubt it. I don't. Because it needs to be done in a way it can be tried by others so we can avoid discussions like this in the future. Hell, maybe we'll come up with a better explanation than 'the meter circuit induction'.

I hope so.   ;D



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It's not as complicated as it may seem...
The thread is locked for now so that I may respond to a few posts.

poynt99,

Your analysis is correct but I think you may wish to dig a bit deeper into the physics. Lewin is famous for dropping bombs to make you think
If it was correct, then your follow-up resistance to it is puzzling.  ???

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There doesn't seem to be any close-ups of the exact setup. So, saying he is wrong or right are only words, unless you are convinced there is no true example of non-conservative induction.   :)
He is wrong and right, depending on your perspective. Magnetic fields are non-conservative, but the emfs induced by them are conservative.

.99
   

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It's not as complicated as it may seem...
@Poynt99
I would have to disagree on several points, first the circuit you have depicted does not resemble the circuit in question in any way as you have incorrectly placed a single fixed voltage source in the circuit. Why would you think you can completely change a circuit to justify the action of another that is nothing like it?, that's crazy.
It is not my circuit btw. This was taken from a web page or book, I don't recall. The purpose of posting it was to get you guys thinking about how KVL is properly applied...in any circuit.

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@Emdevices
I would agree this is too easy --- maybe that is the problem. ;D
Regards
AC
If it was that easy, you perhaps would have figured it out, but that is not the case.

.99
   

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It's not as complicated as it may seem...
I know KVL has exceptions. This was part of my education. It was in the course material and worked on the bench. (On what might be a funny note: I was also taught that magnetic fields are neither conservative(non-dissipative) nor non-conservative(dissipative).  ??? )

I'm just not so sure Lewin's example was truly an example of this case. If it is then the KVL shouldn't be applied and the example is of how laws can be misapplied.
It is not KVL that is being misapplied here.

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From the little bit of detail we have.... .99 could be completely correct by considering the loop inductance to cover a more common solution.
This is on the right track.

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@poytn99
I would disagree, first you are not using a real world test only a simulator, second you have incorrectly used a coil acting as a point source--why not justify your point by just simulating a battery as the source and be done with it?. Changing all the parameters to get the results you like is not what I would call good science and when you do a real experiment with the correct parameters then we can talk about facts.

AC

Again, this is pure nonsense AC. You did not respond to my rebuttal on this, so it is worth stating again.

I've not changed any parameters, but those proposing to insert DC sources, would. Seems you are contradicting yourself here.  ???

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A changing magnetic field is not conservative.
Agreed.

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Assuming no voltage is being induced in the resistors themselves (even though in reality we know that some is in this experiment) we can treat the two conductors as voltage sources. So there are two voltage sources that have equal voltage induced in them because they are identical, and the fields react with them identically. It just so happens that each represents 1/2 Volt end to end. So there is 1/2V across each resistor.
Incorrect. R1 has -0.1V and R2 has 0.9V with the probe polarity as shown.

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So the total series voltage in the circuit then is 1V. Each resistor has +0.25V and -0.25V across it, or 0.5V. So using this measurement method we can now say that the voltage drop from A to D is 0V. Therefore, I can use either A or D to be my reference to any of the four nodes at the resistors and I will get the same reading for each.
Incorrect. R1 has -0.1V and R2 has 0.9V with the probe polarity as shown.

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How is it possible then, that we measure -0.1V and +0.9V ? If KVL holds, then KCL breaks and if KCL holds the KVL breaks. Or if we somehow fix those two to hold, then we must throw out our laws of induction because in this case the only way we can get the circuit to agree, is if we do the math with path dependence, aka Faraday's law which allows that to happen. Or are we to fool ourselves into thinking that somehow the wires make an adjustment to be nonlinear?
It is quite possible and quite explainable. There is something wrong here, but it is not the application of KVL.

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I love the part where he says "Their brains couldn't handle it"
Me too. ;)

.99
   

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It's not as complicated as it may seem...
I see the students are still second guessing the professor.

Perhaps this will help.

http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/lecture-notes/lecsup41.pdf

It specifically addresses the reasons why many textbooks are wrong in their attempts to modify Kirchhoff's Laws.
There is nothing wrong with KVL, and no mod is required.

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We must recognize here that KVL only applies to an electrostatic field. The reason for this is because it is impossible to begin your integral and end your integral at the exact same instant in time. Therefore, if the field changes before you get back to the starting point the loop will not be zero.

This fact is quite evident both in Darren's Scope shots as well as Professor Lewin's scope shots, it is clearly a time changing field i.e. non-conservative. You can tell readily that in both cases (Darren and Lewin) the ground reference for the scope probes is common for both R1 and R2 (on the A side of the resistors).
I can't agree with that. Your concern with "time" in this case is misplaced. It is not an issue. At any instant in time, KVL holds.

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Rewriting the laws to say "instantaneous" or adding unrealistic inductance in order to simulate a voltage source does not solve the problem. In fact, it perpetuates the misunderstanding and obfuscates the core principle of why KVL should be avoided when measuring and calculating nonconservative fields.
This is perfectly correct and realistic. KVL holds, because although the magnetic field is non-conservative, the induced emf is conservative.

.99
   

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No. Essentially you have +1/2V from A to D with respects to R1 and +1/2V from D to A with respects to R2. Therefore, you have +1V from A to A around the closed loop, or +1V from D to D around the closed loop. This is the nature of the nonconservative field in transition inducing an EMF in a loop of conductor.
Incorrect. R1 has -0.1V and R2 has 0.9V with the probe polarity as shown.

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Hi Darren,

First, the Helmholtz coil in unnecessary, all that is needed is for a change in flux to occur in the copper, and this will as the solenoid is energized.
A uniform magnetic field is what is prescribed. You don't get that at the end of a solenoid.

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The proposal by Kirchhoff is that the sum of those two line integrals from A to D and D to A, or alternatively as shown D to A via R1 and D to A via R2 should equal zero. But for that to work E must be stable, and when E is stable there is no induced EMF and if there is no induced EMF then the EMF everywhere is zero and KVL would hold.
KVL holds in both dynamic and static conditions. It is the measurement method that is in error, not the application of KVL.

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Why is it a bad idea to try and force KVL to work in changing magnetic fields by introducing changing power sources to match the drops?
It is perfectly valid to use KVL when the circuit and measurements are fully understood.

.99

NOTE: Apologies to Harvey for losing some of his post. I hit Modify rather than Quote, and I did not reply to some of the post. Sorry, it was not intended.  :-[ Let me know if you have a backup of your posts, and I can put the original text back in.
   

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It's not as complicated as it may seem...
Sorry for the whirlwind of posts....I'm catching up after having given things more thought. ;)

Have at it if you wish.

.99
   
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I would disagree, first you are not using a real world test only a simulator, second you have incorrectly used a coil acting as a point source--why not justify your point by just simulating a battery as the source and be done with it?. Changing all the parameters to get the results you like is not what I would call good science and when you do a real experiment with the correct parameters then we can talk about facts.

@allcanadian
I agree with your points regarding the simulator.

@poynt99
Why are you so convinced that a simulation does not lie?  You can't make a valid scientific argument from a computer simulation if the simulation is contradicted by an experiment!  Protein-folding calculation (a simulation) is now in very advanced stages of research,  but it still makes mistakes due to unknown phenomenon  (water charge interactions, chaperon proteins, trace ions ,etc)

In the same sense, I've mentioned that simulations do not take into account EM scalar waves, but the existence of these waves can be experimentally proven.  Yes I agree simulation is useful, but in reality...  The end truth comes from the bench. The experiment is where science begins.

You must always reconsider your theories when contradicted by experiment -- even 'truths' like special relativity. 

The physicists Günter Nimtz and Alfons Stahlhofen, of the University of Koblenz, claim to have violated relativity experimentally by transmitting photons faster than the speed of light.[38] They say they have conducted an experiment in which microwave photons—relatively low energy packets of light—travelled "instantaneously" between a pair of prisms that had been moved up to 3 ft (1 m) apart. Their experiment involved an optical phenomenon known as "evanescent modes", and they claim that since evanescent modes have an imaginary wave number, they represent a "mathematical analogy" to quantum tunnelling.[38] Nimtz has also claimed that "evanescent modes are not fully describable by the Maxwell equations and quantum mechanics have to be taken into consideration."[39] Other scientists such as Herbert Winful and Robert Helling have argued that in fact there is nothing quantum-mechanical about Nimtz's experiments, and that the results can be fully predicted by the equations of classical electromagnetism (Maxwell's equations).[40][41]

Nimtz told New Scientist magazine: "For the time being, this is the only violation of special relativity that I know of."


http://en.wikipedia.org/wiki/Faster-than-light
   

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I will clarify my questioning of the Lewin demonstration:

I had doubts he performed it correctly to demonstrate the reality of the applications of modified KVL. There still isn't enough evidence available to me, that he did perform it correctly. I have known top electrical engineers and a professor of physics who could not perform the experiment correctly.

For those classifying me as sided on this subject.... Of those posting on the misapplication of KVL, I do agree. Some of the other things stated, I do not agree.

I won't be performing the experiment. There is no point. I know the result will confirm the same things it did when I was required to perform it to earn another stripe. Since then, I have learned there is no amount or quality of data possible to convince most people of anything beyond their experiences short of them actually performing the physical experiment themselves.

When you see me shut-up when references are made to the inductor/spring analogy or...  EMF, V/m, C or C/m2 are being transposed, just know I'm avoiding what might become like this thread.

I may be wrong on some posts I made in this thread. I am not discontinuing participation in this thread because I am wrong about the voltage sources or the voltage drop across the inductors.

KVL, as it is most properly taught, does not apply to any circuit including induction.
Since majority rules on this subject (the majority being the lazy teachers and idiotic book writers) I will not argue with the use of modified KVL as long as it comes up with the correct answer. The same goes for a busted $2 calculator.
Some are satisfied with the correct bottom line. I am not.

.....I think you may wish to dig a bit deeper into the physics.....

.99, I tried to warn you. We are at that impasse again  ;D  I should have made the above quote my last post on this subject.



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It's not as complicated as it may seem...

.99, I tried to warn you. We are at that impasse again  ;D  I should have made the above quote my last post on this subject.

.....I think you may wish to dig a bit deeper into the physics.....


Thanks WW, but the warning is not necessary. However, I will offer your own advice back at ya. ;)

.99
   

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@poynt99
Why are you so convinced that a simulation does not lie? 
SPICE Simulators don't lie, they produce results based on what you give them. If your source data is bad, then the results will be bad. If your source data is good, the results will be good. Source data being the models, and the circuit and sim settings you have input.

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You can't make a valid scientific argument from a computer simulation if the simulation is contradicted by an experiment! 
It can if the experiment has been performed with an error or hidden flaw. You are assuming there is no flaw. That is bandwagon science.

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.99,

SPICE Simulators don't lie, they produce results based on what you give them. If your source data is bad, then the results will be bad. If your source data is good, the results will be good. Source data being the models, and the circuit and sim settings you have input.

We should not forget the capabilities endowed and methods used in the application by the software designer C.C

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That is bandwagon science.

As my hair continues to fall out and loose color, I'm learning much of science is bandwagon science.

All,

I’m going to paraphrase myself from several years ago (Why not? Over the past couple of weeks I’ve found modified or strangely similar versions of my original 1996 ideas dealing with design procedural flaws in power distribution design).
 
The good thing… modified KVL in SPICE (Simulation Program with Integrated Circuit Emphasis) allows less rigorous analog or digital folks quicker and easier circuit analysis. The problem is, any flavor of KVL does not explain or allow us to understand what really happens in the circuit (especially confusing for those well familiar with Faraday’s works). The reason is that physics doesn’t allow an equivalent circuit where the incorrectly applied KVL works. It can't work, because moving the meter physically, without changing the connection points, changes the measured voltage. Digital and poorly informed analog circuit theories do not allow this effect. Faraday does.

This can be demonstrated with any simple loop circuit where two or more loop sections act as secondaries of a transformer with resistors between. Attach a single meter to what we have been calling A & D using connections which allow rotation of that meter and meter circuit around the horizontal axis of the circuit loop. Even if SPICE could handle spatial movement it would fail. As far as I know, Faraday’s laws are not included as an algorithm. Only Faraday's Laws (applied with the meter & meter loop left, right and above or below) can answer that question. The meter will read differently in all four of those positions and every position between without changing the meter’s connection points.
All, without swapping connections or meter polarities!  :o

KVL/KCL only pertain to static situations. They are extremely important and valuable but only fit as a subset of the Laws of Faraday when working with non conservative fields. They are only correct when looking for electric field values (NOTICE: I did not say ‘EMF’. If you don’t know the difference that is the first problem you MUST address.  :()

In the end, the functions of the ‘Real Circuit’ will obey Faraday’s laws because EMF falls in the realm of Faraday’s work, not Kirchhoff, Faraday trumps Kirchhoff, and the Laws of Physics demand obedience.  SPICE, as I know it, will fail to provide accurate results. It was not designed to handle the more wild issues possible. Hell, the first time I used it, the voltage drops across inductors was correct. They were handled as shorts.   O0

KCL/KVL was only attributed to Kirchhoff during his eulogy and thereafter . You’ll have to research his history to find this info. 

I’m not going to put more time into this as the result is always the same. The statement will be repeated “KVL HOLDS!” when it doesn’t even apply. When I see that, it registers in my mind as ‘Faraday’s laws are invalid for this experiment’ . Let’s leave the issue where Faraday’s laws fall apart to a much later time.

When I see statements about ‘voltage drop across inductors’, I know Kirchhoff didn’t consider time so the speaker is confusing the issue. Then, I await the use of the ‘inductor/spring analogy’ contradicting the use of ‘inductor voltage drop of the electric field’.

.99,

May I ask what flavor of SPICE you are using?
If it is open-source I would be interested in seeing the actual algorithm used to simulate and inductor.

This was an easy one: http://www.compliance-club.com/pdf/Issue82.pdf
I would think the folks at Agilent Technologies know a thing or two about network analysis.
Attached is a clipping from that document.


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   
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Hi Darren,

It is unfortunate that my post was altered - I won't hold it against you ;)

They say a picture is worth a thousand words . . . so, attached is a KVL diagram for Lewin's experiment that should illustrate the problem. I think after you review it, you will see the 1/2 V differentials between A and D.

However, the reality is that we measure a 1V closed loop integral from D to D (or from A to A) NOT a 0V integral as this diagram would imply. How do you suppose we use KVL to properly show the reality of the 1V closed loop integral from T0 to T1? Remember, for KVL to hold, we must have a closed loop integral of zero for all T values between T0 and T1 and then we must extrapolate the difference between any two intervals.

It can be seen that each wire represents 1/2 V of induced EMF. These wires are in series as the current in the loop is always in the same direction, so the total induced EMF is 1 V and the loop current is 1 mA. Using ohms law, the wires then exhibit a negative resistance as the EMF is internal for the current flowing within - typical source configuration.

So, the reality is that we have 1/2 V from D to A and another 1/2 V from A to D for a total loop of 1V. Using KVL, we get a negative 1/2 V so that the two EMF values cancel to zero. Can you see any problem with this?

With regards to your Helmholtz assertions, you may want to review Faraday's law which requires a change in flux.  ;)

IMHO, I think the only way you are going to understand what Lewin is trying to teach you is if you remove the wires from the circuit entirely as I have suggested wrt the resistive ring. This way A and D would truly be at the resistive nodes. All that is needed then is for Faraday's law to tell you how much flux is required to produce the 1 mA of current in the ring. Once that eddy current is established, the rest of the reality should become very evident and then I think you will grasp how KVL fails. As long as the wires are there, they keep serving as a crutch as to how the circuit gets the energy. Once they are removed, then the energy must be supplied by some other means, and when you evaluate that I think you will be forced to see Lewn's perspective on this matter.

I wish you the best in your struggle to understand this, and  I wish I could help you in some way to understand it, but at this time I am at a loss of how else to illustrate it in a way you will comprehend.

Cheers,

Harvey





   

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It's not as complicated as it may seem...
.99,

We should not forget the capabilities endowed and methods used in the application by the software designer C.C
I guess I will have to keep repeating this until my dying day; There is absolutely nothing wrong with SPICE. It does what it is designed to do, and as I said in a recent post, it is garbage in, garbage out. Obviously SPICE has it's limitations, but applied correctly with certain details in mind, it serves quite well here in highlighting the limitations of the measuring equipment and methods used by those doing this experiment.
Quote
This can be demonstrated with any simple loop circuit where two or more loop sections act as secondaries of a transformer with resistors between. Attach a single meter to what we have been calling A & D using connections which allow rotation of that meter and meter circuit around the horizontal axis of the circuit loop. Even if SPICE could handle spatial movement it would fail. As far as I know, Faraday’s laws are not included as an algorithm. Only Faraday's Laws (applied with the meter & meter loop left, right and above or below) can answer that question. The meter will read differently in all four of those positions and every position between without changing the meter’s connection points.
All, without swapping connections or meter polarities!  :o
This is getting somewhere. What are the ramifications of this?

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KVL/KCL only pertain to static situations. They are extremely important and valuable but only fit as a subset of the Laws of Faraday when working with non conservative fields. They are only correct when looking for electric field values (NOTICE: I did not say ‘EMF’. If you don’t know the difference that is the first problem you MUST address.  :()

In the end, the functions of the ‘Real Circuit’ will obey Faraday’s laws because EMF falls in the realm of Faraday’s work, not Kirchhoff, Faraday trumps Kirchhoff, and the Laws of Physics demand obedience.  SPICE, as I know it, will fail to provide accurate results. It was not designed to handle the more wild issues possible. Hell, the first time I used it, the voltage drops across inductors was correct. They were handled as shorts.   O0
More bandwagon science.

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I’m not going to put more time into this as the result is always the same. The statement will be repeated “KVL HOLDS!” when it doesn’t even apply. When I see that, it registers in my mind as ‘Faraday’s laws are invalid for this experiment’ . Let’s leave the issue where Faraday’s laws fall apart to a much later time.

When I see statements about ‘voltage drop across inductors’, I know Kirchhoff didn’t consider time so the speaker is confusing the issue. Then, I await the use of the ‘inductor/spring analogy’ contradicting the use of ‘inductor voltage drop of the electric field’.
Your cynicism is duly noted.

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.99,

May I ask what flavor of SPICE you are using?
If it is open-source I would be interested in seeing the actual algorithm used to simulate and inductor.
OrCad PSpice. I think Harvey posted a paper on how SPICE works. There is nothing wrong with the way inductors are modeled in SPICE. Good grief, SPICE has been around since the 80's or so, I would hope that someone would have pointed out the flaw by now if there is one. Besides, I've not seen it disagree with reality in all the time I've been using it. I wouldn't waste your time WW.

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This was an easy one: http://www.compliance-club.com/pdf/Issue82.pdf
I would think the folks at Agilent Technologies know a thing or two about network analysis.
Attached is a clipping from that document.
Appears to be another example of bandwagon science.

WW, you say you're done discussing this, and that you are not going to perform the experiment.

You may be interested to know that as of yesterday, I completed the build of the apparatus based on Lewin's design, and I have also completed several experiments, including a number of them today.

I am happy to report that certain experimental results completely validate the results of my simulation, and that the total loop voltage does sum to zero volts as prescribed by KVL. This renders the electric field as being conservative, contrary to popular belief.

I am also happy to report that certain experimental results correspond precisely with what Lewin has asserted regarding the loop voltage.

It is a matter of perspective, and to a certain degree, philosophy, as to which results you see.

I will be posting a paper, tests, photos, and videos soon, and as time permits. All will be explained, but for now, perhaps a sneak peak of the completed build:

.99
   

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It's not as complicated as it may seem...
Hi Darren,

I wish you the best in your struggle to understand this, and  I wish I could help you in some way to understand it, but at this time I am at a loss of how else to illustrate it in a way you will comprehend.

Cheers,

Harvey

Thanks Harvey, but despite the overwhelming non-confidence vote here, I'm doing quite well on my own.  O0

Stick around and see what unfolds; it's quite possible that you may even learn a thing or two. :) I can assure you that it will be both interesting and controversial.

Darren
   
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Thanks Harvey, but despite the overwhelming non-confidence vote here, I'm doing quite well on my own.  O0

Stick around and see what unfolds; it's quite possible that you may even learn a thing or two. :) I can assure you that it will be both interesting and controversial.

Darren

I must disagree, you have fallen into the same trap as many before you.

If you can understand the attached, then perhaps you can understand KVL as it was intended to be used. He never intended for it to be used in anything other than a static E field.

 :P
   

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I must disagree, you have fallen into the same trap as many before you.

If you can understand the attached, then perhaps you can understand KVL as it was intended to be used. He never intended for it to be used in anything other than a static E field.

 :P

Thanks Harvey. I've already read that paper a couple of times.

You should know that although KVL comes into play as a consequence of the results from one perspective, KVL is not the real issue at hand here. Sorry if I have not made that clear enough.

In other words, and to reiterate, the crux of the problem has nothing to do with KVL.

.99
   
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When I read the Lewin's paper, I remembered a bit more recent paper from Maxim (ics) that I saw some years ago:
http://www.maxim-ic.com/app-notes/index.mvp/id/2238
I had been very impressed by how easy it is to lead wrong measurements!
The Lewin's paper is not original. His point was already emphasized in 1982 by Robert H. Romer in: "What do 'Voltmeters' Measure?" http://ajp.aapt.org/resource/1/ajpias/v50/i12/p1089_s1. Unfortunately pdf not found for free on the web. I had read it after reading the Maxim's paper but unfortunately I have not kept the file. It should be of interest here.



   

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KVL isn't really the issue. The misapplication of physics laws is one of the issues. Another is perspective.

The position sensor example is only one application of this very basic rule. I have individuals working for me who don't really understand something as base as a motor encoder founded upon this example. They all have far more formal civilian education than me. The greatest problem they face is they can't understand that all laws of physics either have examples of where they don't apply or are at risk of being misapplied.

The ramifications of the different meter readings depending upon relative location? I won't hazard a guess. The implications are more than one. The first being that Lewin was correct in everything contained in that lecture. Also the experiment, like all of his experiments covering the lecture, contains every thing emphasized in the lecture.

Beyond that, I'll refrain to avoid effecting any conclusions from .99.

It is incredibly simple.

 


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   
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