Question

In the circuit shown in the figure , there are two parallel plate capacitors each of the capacitance $C$ The switch $S_1$ is pressed first to fully charge the capacitor $C_1$ and then released. The switch $S_2$ is then pressed to charge the capacitor $C_{1}2$. After some time, $S_2$ is released and then $S_3$ is pressed. After some time,

• A. the charge on the upper plate of $C_1$ is $2C{V}_o$
• B. The charges on the upper plate of $C_1$ is $C{V}_o$
• C. The charge on the upper plate of $C_2$ is $0$
• D. The charge on the upper plate of$C_2$ is $-C{V}_o$

Answer 1

Answer: (B)

$C_1=C_2=C$
When $S_1$ is closed.
Charge on $C_1=2VC$
When $S_1$ is released and $S_2$ is closed.
Charge on $C_1$ and $C_2=VC$
When $S_2$ is released and $C_3$ is closed.
Charge on $C_2=CV$

hence answer B is right.