Initially $n$ identical capacitors are joined in parallel and are charged to potential $V$. Now they are…
Initially $n$ identical capacitors are joined in parallel and are charged to potential $V$. Now they are separated and joined in series. Then
Potential difference becomes $n V$ and energy remains the same.
potential difference is $n V$ and energy increases $n$ times
potential difference total energy of combination remains same
potential difference remains the same and the energy increases $n$ times.
Solution
Charge will not flow and potential difference across each capacitor will be $V$. Hence, total potential difference across the series combination will be $n V$.
Total energy will remain same as charge is not flowing.