Q. Two identical capacitors each of capacitance $5\ \mu F$ are charged to potential $2\ kV$ and $1\ kV$ respectively. The $- ve$ ends are connected together. When the $+ ve$ ends are also connected together, the loss of energy of the system is
A) 160 J
B) 0 J
C) 5 J
D) 1.25 J
Explanation
(d) Loss of energy $= \frac{1}{2}\frac{C_{1}C_{2}}{\left( C_{1} + C_{2} \right)}\left( V_{1} - V_{2} \right)^{2}$
$\frac{1}{2}\frac{5 \times 5 \times 10^{- 12}}{(5 + 5) \times 10^{- 6}}(2000 - 1000)^{2}$
$= \frac{5 \times 5 \times 1}{2 \times 10} = \frac{5}{4} = 1.25\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.