Q 12-02-033NEETJEE MainMedium
The plates of an isolated charged capacitor are pulled apart to twice their separation. The work done by the external agent equals
Answer: (B) the initial energy stored
Concept. Isolated: $Q$ fixed; doubling $d$ halves $C$ and doubles $U$.
Step 1. Work. $2U - U = U$, the initial energy.
Answer. The initial energy stored (Option B).
Solution by Sreeraj P, M.Sc Physics