understand and explain experiments that demonstrate: • that a changing magnetic flux can induce an e.m.f. in a circuit • that the induced e.m.f. is in such a direction as to oppose the change producing it • the factors affecting the magnitude of the induced e.m.f.

distinguish between root-mean-square (r.m.s.) and peak values and recall and use Ir.m.s. = I0 / √2 and Vr.m.s. = V0 / √2 for a sinusoidal alternating current