Question

Two concentric spheres of radii $R$ and $r$ have similar charges with equal surface charge densities $\left(\sigma \right)$ . The electric potential at their common centre is

• A. $\sigma / \epsilon _{0}$
• B. $\frac{\sigma }{\left(\epsilon \right)_{0}}\left(R - r\right)$
• C. $\frac{\sigma }{\left(\epsilon \right)_{0}}\left(R + r\right)$
• D. $\frac{\sigma }{4 \pi \left(\epsilon \right)_{0}}\left(R + r\right)$

Answer 1

Answer: (C)

The potential at the centre is the same as that on the surface,
$\therefore \, v \, =\frac{\sigma r}{\epsilon _{0}}+\frac{\sigma R}{\epsilon _{0}}$