Potential difference between the plates of capacitor
V = q / C
Work done to add an additional charge dq on the capacitor
dW = V x dq
= (q/C) x dq
.'. Total energy stored in the capacitor
![](https://www.sarthaks.com/?qa=blob&qa_blobid=5906810897667318771)
When batter is disconnected,
(i) Energy stored will be decreased or energy stored
= 1 / K times the initial energy
(ii) Electric field would decrease
or E = E / K