Electromagnetic induction

Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux.

Related Topics:
Potential difference - Voltage - Conductor - Magnetic flux

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Michael Faraday is generally credited with having discovered the induction phenomenon in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829. Faraday found that the electromotive force (EMF) produced along a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electrical current will flow in any closed conductor, when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. Electromagnetic induction underlies the operation of generators, induction motors, transformers, and most other electrical machines.

Related Topics:
Michael Faraday - 1831 - Francesco Zantedeschi - 1829 - Electromotive force - Magnetic flux - Electrical current - Generator - Induction motor - Transformer - Electrical

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Faraday's law of electromagnetic induction states that:

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: mathcal{E} = {-{dPhi_B} over dt} ,

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where

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:mathcal{E} is the electromotive force (emf) in volts

Related Topics:
Electromotive force - Volt

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:ΦB is the magnetic flux in webers

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For the common, but special case, of a coil of wire, comprised of N loops with the same area, Faraday's law of electromagnetic induction states that

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: mathcal{E} = - N{{dPhi_B} over dt}

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where

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:mathcal{E} is the electromotive force (emf) in volts

Related Topics:
Electromotive force - Volt

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:N is the number of turns of wire

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:ΦB is the magnetic flux in webers through a single loop.

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Further, Lenz's law gives the direction of the induced emf, thus:

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:The emf induced in an electric circuit always acts in such a direction that the current it drives around the circuit opposes the change in magnetic flux which produces the emf.

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Lenz's law is therefore responsible for the minus sign in the above equation.

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