Faraday's Law Is False!

  1. The version of Faraday's Law which purports to include both motional EMF and transformer EMF for circuits is false. There is no theoretical basis for it. Richard Feynman, in his "Lectures on Physics," pointed out the fact that this so-called law, what he called the "flux rule," does not always work and gave two examples. Every textbook and encyclopedia that I know of treats it as a true law. There is a lot of confusion and nonsense related to it. I believe that it is an indictment of the status quo and a scandal.
     
  2. jcsd
  3. Could you post this version of Faraday's Law?

    Thanks
    Matt
     
  4. E=-d[tex]\Phi[/tex]/dt

    Mike
     
  5. Every law is "false" to an extent. As measuring equipment eveolves and we can see at a smaller level, FL will be modified. No one ever said that FL is 100% accurate from now until the end of time.

    FL is based on observed data. I used it hundreds of times to design transformers, chokes, etc. I've had nothing but success with FL. It isn't perfect, but what is?

    Your rant is much ado about nothing. Faraday's law stands tall today and those who wish to knock it down have to produce a better law. Until then, you have no case at all.

    Claude
     
  6. FL is based on observed data. The problem with it has nothing to do with inability to measure small enough values. There are three problems that come to mind at the moment. 1. There are counter examples where it does not work at all. 2. There is no way to incorporated two independent principles into one term of an equation. 3. There is no principle upon which it is based. It is just an ad hoc formulation, like Bode's Law, which works for admittedly most cases, but is just an accident of geometry and math. It is an engineering convenience but is superfluous as a law. It adds nothing to our understanding as the principles of motional EMF and transformer EMF cover every possible case.

    Mike
     
    Last edited: Oct 10, 2009
  7. You might want to look into the quantum description of the phenomenon.

    I wouldn't exactly say that.

    Newton's laws weren't universal -- Relativity had to modify our outlook...but they still hold famous grounding. For that matter we can't really say any law is universal. It is part of what the institution of science is based on - the ability to build on old knowledge with new knowledge.

    In the case of Faraday's law, it did indeed provide us with an understanding in the relation between electricity and magnetism. We were then able to continue on while using this law as a stepping-stone.
     
    Last edited: Oct 10, 2009
  8. Vanadium 50

    Vanadium 50 17,346
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    Same with Ohm's Law. That doesn't work for semiconductors. (And please provide an example where Faraday's doesn't work, so I better understand what you are talking about)

    Same with Ohm's Law, which lumps together resistances caused by electrons and caused by phonons.

    At the risk of sounding like a broken record, one can say the same about Ohm's Law.
     
    Last edited: Oct 11, 2009
  9. ZapperZ

    ZapperZ 29,650
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    You have not shown any valid references to support your argument. And when I say valid sources, I mean published, peer-reviewed sources, which is the only type we will accept in this forum. Till you can do that, you are violating the speculative post rules from our PF Guidelines that you had agreed to.

    Please post your required sources in the VERY NEXT post, or this discussion will end immediately.

    Zz.
     
  10. Dadface

    Dadface 2,069
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    I wonder if this is referring to the Faraday paradox which, as I understand it, is only an apparent paradox.I tried a quick google and shall return there later since it looks quite interesting
     
  11. You have only to find a textbook that treats all of Maxwell's equations in their entirety (like Feynman's volume II). He's got a nice big table of "true in general" vs. "true only in restricted circumstances".

    The objection to the falseness of this particular "law" is curious. So much of how physics is taught is this way. We start with Coulomb's law and find no, that's false (need maxwell's equations) ; pendulum as harmonic oscillator (false: only for small angles) ; Newton's laws ... (false: need relativity) ; classical mechanics (false: need QM) ; QM (need QFT?) ; ...

    I view my physics studies as an attempt to learn progressively less false models of the world.
     
  12. Peeter,

    Very well put.

    Thanks
    Matt
     
  13. I am not speculating. I am repeating what has already been published by a distinguished source. Ironically, Faraday's disk dynamo, or homopolar generator, is a counter example, as pointed out by Richard Feynman in his "Lectures on Physics." I would think that someone of his status would be the equivalent of a peer-reviewed source. By the way, is there a published peer-reviewed source that states or proves that Faraday's Law is based upon an established physical principle?

    Mike
     
  14. Would you please quote exactly what Feynman said about FL? You suggest that Feynman questions the validity of FL. but you must elaborate in detail. FL is pretty simple. v = -N*d(phi)/dt, or in vector form, curl E = -dB/dt. What part is non-valid? Is there another term needed, or factor, or both? If that equation is wrong, please illuminate us with the right one. If you can do that, and have said equation verified through independent testing, then you have something. Otherwise, you're just "talking the talk". I don't think you're as clever as you think you are. You bluff and bluster as if you hold 4 aces, when all you have is a mere pair of deuces, or less.

    Claude
     
  15. ZapperZ

    ZapperZ 29,650
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    What "established physical principle" is Coulomb's law is based on? What established physical principle is the symmetry of our universe based on? What established physical principle is the Schrodinger equation based on?

    You still haven't given any valid references. What "published by distinguished source" are you talking about? Give exact references the way they do in peer-reviewed sources.

    Zz.
     
  16. I think Feynman's lectures are acknowledged as a valid source in the expert literature, wouldn't you agree?

    I think you will find Feynman also points out that Newton's laws are false. (And that Schroedinger's equation is also false.)

    And yet, modern textbooks still teach Newton's laws (and Schroedinger's equation). Is that a scandal? An indictment? For example, are all of these authors completely unaware of relativity theory? Or are you just getting unnecessarily over-dramatic about the fact that it is practical to first teach the parts that are simple and widely applicable (and only afterwards to build upon it by teaching the superseding knowledge, which is more abstract, difficult, and not directly relevant to daily experience). Perhaps you're also mistaken about what scientists mean when they use the term "law"? (And as for implying Feynman's course is separate from the status quo...)

    Apparently (linking to a direct quote) the former, not the latter. (In this particular context.)
     
    Last edited: Oct 11, 2009
  17. russ_watters

    Staff: Mentor

    Yes, but the OP has not provided a valid reference, which means a direct quote and a link to where it may be read/heard in context. That's the only way for other users to judge the quote for themselves. 'Take my word for it' isn't a reference.

    Unless the reference is posted so the others here can know what the heck the OP is talking about, this thread will have to be locked.
     
  18. I've put a link in above, but seriously, how will an exact page citation help? Anyone who has the volumes need only look up the homopolar generator in their index anyway, anyone else is still stuck either way.
     
  19. ZapperZ

    ZapperZ 29,650
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    What the OP did was similar to saying that he found it PRL. PRL is a respectable journal, but the WAY it is cited is not a VALID reference. Besides, is this what the OP meant as one of the "distinguished source"? If you read the post, it doesn't sound like it.

    Zz.
     
  20. If this is what you gotten out of reading Feynman's lecture notes 17-1 and 17-2, you've misunderstood.
     
  21. I have no access to Feynman's "Lectures on Physics" at this time. There is a link to the relevant pages. It is link No.1 of Steve's 20:39 15 September 2009 comment in item No.48 of the discussion page to the article "Faraday's law of induction" at Wikipedia. The URL that came up is http://student.fizika.org/~jsisko/Knjige/Opca Fizika/Feynman Lectures on Laws of Induction.pdf. [When I preview this post I find that this URL is shortened for some reason.]

    As to what part of a the equation (or equations) is false, the answer is that the equation is simply false. It cannot be broken down into parts. If it had the partial derivative instead of the ordinary one, it would be one of Maxwell's Laws, the one responsible for transformer EMF. What it lacks is a part for motional EMF. Transformer EMF and motional EMF are examples of the kind of principles to which I was referring.

    The homopolar generator is a counter example to Faraday's Law. It is obviously an example of a steady-state situation when it is running at a constant speed. There is no time variation in the magnetic flux linking the circuit. In fact, to at least a first approximation, the magnetic flux lines are parallel to the plane of the circuit. Faraday's Law gives a value of zero for the EMF, but homopolar generators do work.

    Mike
     
    Last edited: Oct 11, 2009
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