Q. Two insulates metallic spheres of $3\mu F$ and $5\mu F$ capacitances are charged to $300V$ and $500V$ respectively. The energy loss, when they are connected by a wire is
A) $0.012\ J$
B) $0.0218\ J$
C) $0.0375\ J$
D) $3.75\ J$
Explanation
(c) $\mathrm{\Delta}U = \frac{1}{2}\frac{C_{1}C_{2}\left( V_{2} - V_{1} \right)^{2}}{(C_{1} + C_{2})} = \frac{1}{2} \times \frac{(3 \times 5) \times 10^{- 12} \times (500 - 300)^{2}}{(3 + 5) \times 10^{- 6}}$
$= \frac{15 \times 10^{- 12} \times 4 \times 10^{4}}{2 \times 8 \times 10^{- 6}} = 0.0375\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.