Test: Electricity and Circuits - Class 6 MCQ

When the circuit is closed, an electric current starts flowing in the circuit from the positive terminal of battery. The current which passes through bulb P is the sum of current flowing in bulbs Q and R. As the brightness depends upon the current flowing through the bulb, so P will be bright but Q and R will be dim.

Since switch S₂ is open and S₁ is closed, the current will pass through bulb Y. But the circuit is incomplete and there is no complete path for current to flow for bulb X. Hence, only bulb Y will alow.

All as the bulbs are in series and bulb R is fused, so the circuit will not be complete and all the bulbs P, Q, R and S will not glow.

 If bulb P fuses, the circuit of bulb Q breaks while the circuit of bulbs R and S remain same as before. Hence Q will not lit while R and S will remain lit.

The torch is not glowing because either its bulb is fused or cells are connected wrongly or metal spring of torch does not make proper contact with the cell.