In which of the following cases e.m.f. is induced?

(i) A current is started in a wire held near a loop of wire.

(ii) The current is switched off in a wire held near a loop of wire.

(iii) A magnet is moved through a loop of wire.

(iv) A loop of wire is held near a magnet.

A conductor is moved in a varying magnetic field. Name the law which determines the direction of current induced in the conductor.

Complete the sentence —

An a.c. generator changes the ___ energy to ___ energy.

What energy conversion does take place in a generator when it is in use?