Question

A capacitor of capacitance $700\, pF$ is charged by $100\, V$ battery. The electrostatic energy stored by the capacitor is

• A. $2.5 \times 10^{-8} \, J$
• B. $3.5 \times 10^{-6} \, J$
• C. $2.5 \times 10^{-4} \, J$
• D. $3.5 \times 10^{-4} \, J$

Answer 1

Answer: (B)

Here, $C=700 \, PF =700\times10^{-12}\, F$,
$V=100\,V$
Energy stored
$U=\frac{1}{2}CV^{2}=\frac{1}{2}\times700\times10^{-12}\times\left(100\right)^{2}$
$=3.5\times10^{-6}\, J$