Question

A parallel plate capacitor of capacitance C is charged to a potential V. It is then connected to another uncharged capacitor having the same capacitance.Find out the ratio of the energy stored in the combined system to that stored initially in the single Capacitor.

Answer 1

Energy stored in a capacitor 

Capacitance of the (parallel) combination

= C + C = 2C

Here, the total charge, Q, remains the same :