A coil of insulated copper wire is connected to a galvanometer. What happens if a bar magnet is :
(a) pushed into the coil ?
(b) withdrawn from inside the coil ?
(c) held stationary inside the coil ?
Give reasons for your observation.

Explanation

(a) When a bar magnet is pushed into the coil of insulated copper wire connected to a galvanometer, an induced current is set-up in the coil due to change of magnetic field through it. As a result, galvanometer gives a deflection (say towards left).
(b) When the bar magnet is withdrawn from inside the coil, again an induced current is set up in the coil due to change of magnetic field through it. As a result galvanometer gives a deflection in the reverse direction. (say towards right).
(c) If the bar magnet is held stationary inside the coil, then there is no induced current in the coil, because there is no change in magnetic field through it. As a result, galvanometer does not show any deflection.