Question

A charge $Q$ is placed inside the sphere of radius $a$ then electric potential (magnitude) at the surface of the sphere will be, (symbols have their usual meaning)

• A. $\frac{KQ}{a}$
• B. $\frac{2KQ}{a}$
• C. $\frac{\frac{1}{2}KQ}{a}$
• D. $0$

Answer 1

The correct option is A $\frac{KQ}{a}$

We know that the charge inside a conductor is zero. When a charge $Q$ is placed inside the conductor, $-Q$ will induce on inner surface and $+Q$ will induce on outer surface such that total charge inside the conductor is zero.

Thus, the charge accumulated on the surface of sphere will be $Q$.

For a spherical conductor, the electric potential at surface $=$ the electric potential inside sphere $=\frac{kQ}{a}$