Two coils 1 and 2 of insulated copper wire having large but different number of turns are wound over a cardboard cylinder. Coil 1 is connected to battery and a plug key. Coil 2 is connected to a galvanometer.
How will the galvanometer reading change when

(i) key is plugged in and

(ii) key is taken out? Give reason for your answer in each case.

(i) Whenever the key is plugged in or out, a momentary deflection is shown in the galvanometer. It is because of the phenomenon of electromagnetic induction.
(ii) Whenever the key is plugged in or out the magnetic field linked to the coil 2 changes and a current is induced in it.