Question

An automobile spring extends $0.2 \,m$ for $5000\, N $ load. The ratio of potential energy stored in this spring when it has been compressed by $0.2\, m$ to the potential energy stored in a $ 10\,\mu F $ capacitor at a potential difference of $10000\, V$ will be

• A. 1/4
• B. 1
• C. 1/2
• D. 2

Answer 1

Answer: (B)

When a force of $F$ newton is applied the potential energy is given by
$U=\frac{1}{2} F x$
Energy stored by capacitor is $\frac{1}{2} C V^{2} .$
$\therefore $Ratio is $\frac{\frac{1}{2} F x}{\frac{1}{2} C V^{2}}$
$=\frac{5000 \times 0.2}{10 \times 10^{-6}\left(10^{4}\right)^{2}}=1$