Question

In the figure shown, the electric potential energy of the system is $(q$ is at the centre of the conducting neutral spherical shell of inner radius $a$ and outer radius $b$ )

• A. 0
• B. $\frac{k q^{2}}{2 b}$
• C. $\frac{k q^{2}}{2 b}-\frac{k q^{2}}{2 a}$
• D. $\frac{k q^{2}}{2 a}-\frac{k q^{2}}{2 b}$

Answer 1

Answer: (C)

$U=\frac{-k q q}{a}+\frac{k q q}{b}-\frac{k q q}{b}+\frac{k q^{2}}{2 a}+\frac{k q^{2}}{2 b}$
$=\frac{k q^{2}}{2 b}-\frac{k q^{2}}{2 a}$