Question

Figure shows two coils X and Y. The coil X is connected to a battery S and a key K. The coil Y is connected to a galvanometer G.

When the key K is closed. State the polarity

1. at the end B of the coil X,
2. at the end C of the coil Y,
3. at the end C of the coil Y if the coil Y is (a) moved towards the coil X, (b) moved away from the coil X.

Answer 1

(a) At end B of coil X: North pole (N).

(b) At end C of coil Y: North pole (N) momentarily when key K is closed. Once the current becomes steady, there is no induced polarity.

(c) When coil Y is:

1. Moved towards coil X: North pole (N) at C.
2. Moved away from coil X: South pole (S) at C.

Reason: According to Lenz’s law, the induced current opposes the change in magnetic flux producing it.