For a uniformly charged thin spherical shell,the electric potential $(V)$ radially away from the center $(O)$ of the shell can be graphically represented as:

Two charges $8 \ \mu C$ each are placed at the corners $A$ and $B$ of an equilateral triangle of side $0.2 \ m$ in air. The electric potential at the third corner $C$ is

Derive an expression for the electric potential at a distance $r$ from a positive point charge $Q$.

Choose the $CORRECT$ option.

When a charge of $0.01 \ C$ is moved from point $A$ to point $B$ against an electric field,the work done is $15 \ J$. The potential difference $(V_B - V_A)$ is ....... $V$.

Four equal point charges $Q$ are placed in the $xy$ plane at $(0, 2), (4, 2), (4, -2)$ and $(0, -2)$. The work required to put a fifth charge $Q$ at the origin of the coordinate system will be