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 What will happen if a bar magnet is (i) pushed into the coil, (ii) withdrawn from inside the coil, (iii) held stationary inside the coil.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

Hint: As there is no attached battery in the loop, current would be induced instead by the current produced in the insulated copper wire. That will modify the magnetic field across the coil. Therefore, a certain current in the coil may be produced.

Stepwise solution:
Given,
A coil of insulated copper wire is connected to a galvanometer.
If a bar magnet is (i) pushed into the coil

(i) If the magnet is forced into the coil, the galvanometer tries to deflect in such a direction, and then an electromotive force is established in the coil, as per Faraday's rule. It causes current due to electromagnetic induction as the magnet is moved near a bar magnet.

If a bar magnet is (ii) withdrawn from inside the coil

(ii) The current is generated in the coil as the bar magnet is removed from within the coil of the shielded copper wire again; however it is in the opposite direction this time. The galvanometer tries to deflect in the reverse direction when the magnet is removed.

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

(iii) There is no current caused when a bar magnet is kept stationary within the coil, that is why the galvanometer would display no deflection.

Note:
An electrical current throughout the coil would be generated if we held the bar magnet stationary and shifted the coil back and forth inside the magnetic field. So we will induce a current and voltage inside the coil either by moving the wire or changing the magnetic field so this phase is known as Electromagnetic Induction which is the underlying concept of transformer, motor which generates operation.