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 withdrawn from inside the coil,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?

A coil of insulated copper wire is connected to a galvanometer. If a strong bar magnet is-

$(i)$. If a bar magnet is pushed into the coil:

On pushing the bar magnet into the coil there is a change in the magnetic field. So an induced current is set up in the coil, then a momentary deflection in the needle of the galvanometer to one side $(left/right)$ is observed.

$(ii)$. If a bar magnet is withdrawn from inside the coil:

When the bar magnet is withdrawn from inside the coil there is a change in the magnetic field again, a new induced current is set up in the coil. So,  there is a momentary deflection in the needle of the galvanometer observed, but now in the opposite direction.

$(iii)$. If a bar magnet is held stationary inside the coil:

When the bar magnet is held stationary inside the coil, then there is no change in the magnetic field. So no new induced current in the coil. Therefore, there is no deflection observed in the galvanometer.