Question

For the circuit shown in following fig., which of the following statements is true?

• A. With $S_1$ closed, $V_1=15V,V_2=20V$
  
• B. With $S_1,S_2,S_3$ closed, $V_1=V_2=0V$
  
• C. With $S_{1}and{S}_2$ closed $V_1=V_2=0$
  
• D. With $S_{1}and{S}_3$ closed $V_1=30V$ and $V_2=20V$

Answer 1

The correct option is B

With $S_1,S_2,S_3$ closed, $V_1=V_2=0V$

The charge stored in C1 = $C_1\ast V_1$ = 60pC .
The charge stored in C2 = $C_2\ast V_2$ = 60pC .
When S1, S2 and S3 are closed, the first and last plates of C1 and C2 respectively are at zero (or same) potential. Also, the charge stored in C1 and C2 were equal before closing of the switch such that after closing of the switch, the charge on each of the plates is zero.
So, V1 = V2 = 0 after closing of switch S1, S2 and S3.