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| Electromagnetic induction. |
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| It is, in general, acknowledged that the theoretical treatment of electromagnetic induction phenomena presents some problems when part of the electrical circuit is moving. Some authors speak of exceptions to the flux rule [1], others save the flux rule by ad hoc choices of the integration line over which the induced emf is calculated. |
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| A general law for electromagnetic induction phenomena is derived by defining the induced emf as the integral over a closed loop of the Lorentz force acting on a unitary positive charge. The induced emf is the product of two independent phenomena: time variation of magnetic field and effects of magnetic field on moving charges. The flux rule is neither a causal law nor a field-law: it is a rule for calculation that yields, but not always, the correct result. For a recent, complete treatment, see here. A survey of Faraday and Maxwell writings shows that the taking root of the "flux rule" constitutes an open historical problem [4], [5], [6]. (g.g.) |
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[1] R. Feynman, R. Leighton and M. Sands, The Feynman Lectures on Physics, vol. II, (Addison Wesley, Reading, Ma., 1964 ), pp. 17-2,3.
[2] A general law for electromagnetic induction, G. Giuliani,
EPL, 81 (2008) 60002.
[3] On electromagnetic induction G. Giuliani. Published in Physics e-Print archive on Thursday, 3 August 2000.
[4] Electromagnetic induction: physics and flashbacks. G. Giuliani, XXI Congresso Nazionale di Storia della Fisica, Cosenza, 2001.
[5] Induzione elettromagnetica: fisica e flashbacks. G. Giuliani, La fisica nella scuola, quaderno XIV, 2002.
[6] Vector potential, electromagnetic induction and "physical meaning", G. Giuliani, 2010. This is an author-created, un-copyedited version of an article accepted for publication in European Journal of Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at 2010 Eur. J. Phys. 31 871 |
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