Question

A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is

(i) pushed into the coil,

(ii) withdrawn from inside the coil,

(iii) held stationary inside the coil?

Answer 1

Galvanometer

1. A galvanometer is a device used to detect a small electric current or measure its magnitude. On placing a current-carrying coil in an external magnetic field coil experiences magnetic torque. The angle through which the coil is deflected due to the magnetic torque effect is proportional to the magnitude of current in the coil.
2. When a bar magnet is pushed into the coil, an electric current will be induced in the coil due to electromagnetic induction.
3. When a bar magnet is withdrawn from inside, again current will be induced in the copper wire due to electromagnetic induction but this time the direction of current will be reversed in the galvanometer.
4. When a bar magnet is held stationary inside the coil, no current is induced.

(i) Hence, the needle of the galvanometer shows a momentary deflection in a particular direction.

(ii) Hence, the needle of the galvanometer shows a momentarily in the opposite direction.
(iii) Hence, The needle of the galvanometer shows no deflection.