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

When S₃ is closed, due to attraction with opposite charge, no flow of charge takes place through S₃. Therefore, potential difference across capacitor plates remains unchanged or V₁ = 30 V and V₂ = 20 V.

Alternate Solution

Charges on the capacitors are

q₁ = (30)(2) = 60 pC

and q2 = (20)(3) = 60 pC

or q₁ = q₂ = q (say)

The situation is similar as the two capacitors in series are first charged with a battery of emf 50 V and then disconnected.

∴ When S₃ is closed, V₁ = 30 V and V₂ = 20 V