Question

Four identical bulbs $A,B,C,D$ are connected in a circuit as shown in figure. Whenever any bulb fails, then it cannot conduct current through it. Then -

• A. Brightness of bulb $C$ is highest
• B. If $C$ fails, brightness of bulb $D$ increases
• C. If $C$ fails, brightness of all bulbs remain same
• D. If $A$ fails, $B$ will not glow

Answer 1

Answer: (A), (C), (D)

The correct options are
A Brightness of bulb $C$ is highest
C If $C$ fails, brightness of all bulbs remain same
D If $A$ fails, $B$ will not glow

Here $D$ is short circuited, so potential difference across $D$ in zero.
$C$ is directly connected across the battery, potential difference across $C$ in maximum. Brightness of bulb $C$ is highest.

As $C$ is connected in parallel to combination of $A$ and $B$ which are connected in series so, if $A$ fails, then $B$ also fails. If $C$ fails, brightness of all bulbs remain same