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

Options

A. with `S_(1) closed V_(1)=15V, V_(2)=20V`
B. with `S_(1) closed, V_(1)=V_(2)=25V`
C. with `S_(1) and S_(2) closed, V_(1)=V_(2)=0`
D. with `S_(1) and S_(3) closed, V_(1)=30V,V_(2)=20V`

Answer

D

Explanation

When `S_3` is closed due to attraction with opposite charge,no flow of charge take place through `S_3` potentoal difference across capacitor plates remains uncharged or `V_1= 30 V and V_2= 20 V`
Alternate sollution
`q_1=(30)(2)=60pC`
and `q_2=(20) (3)= 60pC`
or `q_1=q_2=q(say)`
The situation is simillar as the two capacitors in the series are first charged with a battery of emf 50 v and then disconnected
`therefore` when `S_3` is closed `V_1=30 V` and `V_2=20 V`