Q.
In the given figure. $A,\ B\ and\ C$ are three identical bulbs. When the switch $S$ is closed
A) The brightness of bulb $A$ does not change and that of $B$ decreases
B) The brightness of bulb $A$ increases and that of $B$ decreases
C) The brightness of $A$ increases bulb $B$ does not glow
D) The brightness of both bulbs $A\ not\ B$ decrease
Explanation
(b) When switch $S$is pressed, the resistance of circuit decreases. Hence, the current in bulb A will increase but the current in bulb $B$ will decrease. Hence, the brightness of bulb $A$ will increase and that of bulb $B$ will decrease.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.