Science Education Home Home Teachers Students Games Videos VA SOL Programs

Jefferson Lab's Workbench Projects


Faraday's law of induction states that a changing magnetic flux creates an induced electromotive force. In equation form, Faraday's law of induction is:

The induced EMF is proportional to the time rate of change of magnetic flux.

where the minus sign indicates that the direction of the induced electromotive force opposes the change of magnetic flux. This opposition becomes apparent in a closed, conductive circuit, where the induced electromotive force gives rise to an electric current whose magnetic field opposes the change of magnetic flux. This effect is stated as Lenz's Law: An induced electromotive force always gives rise to a current whose magnetic field opposes the original change in magnetic flux. For example, if the magnetic flux within a certain region is increasing, an electric current will be established in such a way as to reduce the magnetic flux, assuming a closed, conductive path exists through which the induced current can flow.

Citation and linking information

For questions about this page, please contact Steve Gagnon.