Three identical bulbs A, B and C are given. What changes occur in the brightness of bulbs A and B, when the switch S is closed?
ABrightness of A increases but that of B decreases.
BBrightness of A remains the same but that of B
decreases.
CBrightness of both A and B decreases.
DBrightness of both A and B increases.
Ans 1: (Master Answer)
A
For the identical bulbs , the brightness of the bulbs depend upon the current flowing through them or the potential difference across them.
In the given circuit when the switch S is closed , due to parallel combination of bulbs B and C net resistance of the circuit decreases and hence the current through bulb A increases.While the current is divided between bulbs B and C .
Therefore the brightness of bulb A increases , B decreases and bulb C starts glowing.