Q 12-02-125JEE MainJEE Main 2022 (27 Jun, Shift 1)Easy
A capacitor of capacitance $50$ pF is charged by $100$ V source. It is then connected to another uncharged identical capacitor. Electrostatic energy loss in the process is ______ nJ.
Numerical value type. Enter your answer.
Answer: 125
Initial energy: $U_i = \frac12CV^2 = \frac12(50\times10^{-12})(100)^2 = 250$ nJ.
The charge is shared equally, so the common voltage is $50$ V:
$$U_f = 2\times\frac12(50\times10^{-12})(50)^2 = 125\ \text{nJ}$$
Energy lost $= 250 - 125 = 125$ nJ.
Solution by Sreeraj P, M.Sc Physics