Question

In the arrangement shown in figure, there are two coils wound on a non-conducting cylindrical rod. Initially, the key is not inserted. Then, the key is inserted and later removed. Then, (a) the deflection in the galvanometer remains zero throughout. (b) there is a momentary deflection in the galvanometer but it dies out shortly and there is no effect when the key is removed. (c) there are momentary galvanometer deflections that die out shortly, the deflections are in the same direction. (d) there are momentary galvanometer deflections that die out shortly, the deflections are in opposite directions. Thus, the galvanometer shows momentary deflections in opposite directions. [NCERT Exemplar]

Answer 1

After removing key (d) there are momentary galvanometer deflections that die out shortly, the deflections are in opposite directions.

Explanation:

• When the current flows through the first coil, changes in magnetic field in second coil occurs which induces electromotive force in second coil.
• When the key is inserted the magnetic field increases and when the key is removed then the magnetic field decreases.
• Thus, the current flowing in the coil is only momentary and it flows in opposite direction.
• The deflection is the galvanometer is momentary and it stop after the key is taken. Since, the current flows in opposite direction, the deflection is also taking place in opposite direction.