Question

In the figure, a potential of $+1200\, V$ is given to point $A$ and point $B$ is earthed. What is the potential at the point $P$ ?

• A. 100 V
• B. 200 V
• C. 400 V
• D. 600 V

Answer 1

Answer: (C)

Given circuit can be reduced as follows

In series combination, charge on each capacitor remains same.
So using $Q=C V$
$\Rightarrow C_{1} V_{1}=C_{2} V_{2}$
$\Rightarrow 3\left(1200-V_{p}\right)=6\left(V_{P}-V_{B}\right)$
$\Rightarrow 1200-V_{p}=2 V_{p}$
$\left(\because V_{B}=0\right)$
$\Rightarrow 3 V_{p}=1200$
$\Rightarrow V_{p}=400$ volt