State the principle of an electric generator.

State whether the following statements are true $(T)$ or false $(F)$.
$(a)$ An electric motor converts mechanical energy into electrical energy.
$(b)$ An electric generator works on the principle of electromagnetic induction.

Two circular coils $A$ and $B$ are placed close to each other. If the current in the coil $A$ is changed,will some current be induced in the coil $B$? Give reason.

In the activity,how do we think the displacement of rod $AB$ will be affected if:
$(i)$ current in rod $AB$ is increased;
$(ii)$ a stronger horse-shoe magnet is used; and
$(iii)$ length of the rod $AB$ is increased?

When does an electric short circuit occur?

$A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is withdrawn from inside the coil?