Q 12-02-030NEETJEE MainMedium
A $4\ \mu$F capacitor charged to $50$ V is connected to an uncharged $6\ \mu$F capacitor. The common potential and the energy lost are
Answer: (C) $20$ V and $3$ mJ
Concept. Charge conserved; loss $= \dfrac12\dfrac{C_1C_2}{C_1 + C_2}(\Delta V)^2$.
Step 1. Common potential. $\dfrac{200}{10} = 20$ V.
Step 2. Loss. $\dfrac12 \times 2.4 \times 10^{-6} \times 2500 = 3$ mJ.
Answer. $20$ V and $3$ mJ (Option C).
Solution by Sreeraj P, M.Sc Physics