The production of an electromotive force in a conductor when there is a change of magnetic flux linkage with the conductor or when there is relative motion of the conductor across a magnetic field. The magnitude of the e.m.f. is proportional (and in modern systems of units equal) to the rate of change of the flux linkage or the rate of cutting flux dΦ/dt; the sense of the induced e.m.f. is such that any induced current opposes the change causing the induction, i.e. E = −dΦ/dt. See Faraday's laws; Lenz's law; Neumann's law; inductance.