Electrostatic Potential and Capacitance

A capacitor of capacity C1 charged up to V volt and then connected to an uncharged capacitor of capacity C2. The final potential difference across each will be

1. C1VC1+C2
2. C2VC1+C2
3. (1- C2C1 )V
4. (1+ C2C1 )V

Answer

(1) C1VC1+C2

Solution

Initial charge on C1: Q = C1V

On connecting, the charge is shared until both are at the same potential V' (the capacitors are in parallel).

Conservation of charge:

C1V = (C1 + C2)V'

∴ V' = C1VC1+C2

Answer: (1)