Re: Error in Wikipedia article: Faraday's law of induction

On Mon, 14 Jul 2008 11:16:39 -0700 (PDT) blackhead <larryharson@xxxxxxxxxxxx> wrote:
| On 12 Jul, 12:19, phil-news-nos...@xxxxxxxx wrote:
|> It seems there is an error in this Wikipedia article:
|>
|> ? ?http://en.wikipedia.org/wiki/Faraday%27s_law_of_induction
|>
|> Faraday's law says the induced EMF is in proportion to the rate of CHANGE
|> (my emphasis) of the magnetic flux. ?The article describes this much OK.
|> Later on, the article then says:
|>
|> ? ? In the case of motional EMF, the idea is to move all or part of the
|> ? ? circuit through the magnetic field, for example, as in a homopolar
|> ? ? generator.
|>
|> But this last case is a situation where the magnetic flux does not change.
|> Isn't this the aspect that Faraday saw as a paradox because it did not obey
|> his law of induction? ?Apparently he realized that no flux change happened
|> when he rotated the magnets with the rotating disk in his unipolar generator.
|>
|> As I understand all this, there are TWO ways to induce electricity from a
|> magnetic field:
|>
|> 1. ?A conductor at a right angle to the magnetic field alignment experiencing
|> ? ? a change in the magnetic field flux density (strength). ?[Faraday's law
|> ? ? of induction]
|>
|> 2. ?Motion of a conductor at right angle to the magnetic field alignment and
|> ? ? simultaneously at right angle to the line of the conductor. ?[Fleming's
|> ? ? right hand rule, Lorentz force law]
|
|
|> The article seems to be trying to convert everything into one.
|
| Which is correct, as far as Faraday's Law is concerned. The induced
| EMF around a closed circuit is equal to the rate of change of flux
| through the circuit and independent of whether it's the conductor or
| the magnetic filed which is "moving".

But the Lorentz law is not about change of flux.

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Relevant Pages

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