Q. $n$ identical condensers are joined in parallel and are charged to potential $V.$ Now they are separated and joined in series. Then the total energy and potential difference of the combination will be
A) Energy and potential difference remain same
B) Energy remains same and potential difference is $nV$
C) Energy increases $n$ times and potential difference is $nV$
D) Energy increases $n$ times and potential difference remains same
Explanation
(b) According to energy conservation, energy remains the same
$\Rightarrow U_{parallel} = U_{series} \Rightarrow \frac{1}{2}(nC)V^{2} = \frac{1}{2}\left( \frac{C}{n} \right)V^{'2} \Rightarrow V^{'} = nV$
[$V^{'} =$ potential difference across series combination]
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.