Normally,a red colour cable is used for the live wire in domestic electrical circuits.

If the key in the arrangement (Figure) is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane $ABCD$,the lines are

$A$ compass needle is placed near a current-carrying wire. State your observation for the following cases and give the reason for the same in each case:
$(a)$ Magnitude of electric current in the wire is increased.
$(b)$ The compass needle is displaced away from the wire.

What is meant by the term "magnetic field lines"? List two properties of magnetic field lines.

State the energy change which takes place when a magnet is moved inside a coil having a galvanometer at its ends. Name this phenomenon.

Draw an appropriate schematic diagram showing common domestic circuits and discuss the importance of a fuse. Why is it that a burnt-out fuse should be replaced by another fuse of identical rating?