Question

Observing that the bulb does not glow in the circuit shown in the following figure A, Boojho changed the circuit as shown in the following figure B. He observed deflection in the magnetic compass.

A	B

1. What does the deflection in magnetic compass indicate?
2. Why did the bulb not glow in the following figure A?
3. What would be the effect of increase in the number of turns in the coil wound around the magnetic compass in the following figure B?
4. What will be observed if the number of cells are increased in the circuit shown in the following figure B?

Answer 1

1. The deflection in the magnetic compass shows that the current is flowing in the circuit.
2. The bulb did not glow, because the current passing through the circuit could be too weak to make it glow. Also, it may happen because of other reasons, like bulb may be fused or the connections may be loose.
3. Increase in the number of turns in the coil wound around the magnetic compass would increase the magnetic field around the magnetic compass which will result in an increase in the deflection in magnetic compass.
4. Increase in the number of cells will further increase the deflection in magnetic compass.