Question

A $ 15\,pF $ capacitor is connected to a $ 60\,V $ battery. How much electrostatic energy is stored?

• A. $ 2.77\times 10^{-8}\,J $
• B. $ 1.77\times 10^{-8}\,J $
• C. $ 2.35\times 10^{-8}\,J $
• D. $ 1.35\times 10^{-8}\,J $

Answer 1

Answer: (A)

Electrostatic energy $U=\frac{1}{2} C V^{2}$
$=\frac{1}{2}\left(15 \times 10^{-12}\right) \times(60)^{2}$
$=\frac{1}{2} \times 15 \times 36 \times 10^{-12} \times 10^{2}$
$=270 \times 10^{-10}$
$=2.70 \times 10^{-8} J$