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:
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.