Question

An equipotential surface that surrounds a + 5.0 μC point charge has a radius of 5.0 cm. What is the potential of this surface? *

Answer 1

The potential of electric field due point charge

$$V=k\frac{q}{r}$$

$$V=9\times 10^9\times\frac{5.0\times 10^{-6}}{0.05}=9\times 10^5\:\rm V$$