Obtain an expression for work done in rotating an electric dipole in uniform electric field. Write an expression for total electric potential energy of an electric dipole in uniform electric field and suggest its position for stable and most unstable equilibrium state.

Calculate in the given figure: work done in taking the same amount of negative charge from $A$ to $B$, $(OA = 0.10 m, OB = 0.20 m)$.

A charge $\mathrm{A}$ of $8.0 \mathrm{\mu C}$ is situated at a distance of $1.00$ metre from a charge $\mathrm{B}$ of $-2.0 \mathrm{\mu C}$, as shown. Calculate the potential at the mid-point $\mathrm{C}$ between $\mathrm{A}$ and $\mathrm{B}$.  Also calculate the potential at $\mathrm{D}$ which is at a distance of $0.80 \mathrm{m}$ from $\mathrm{A}$ and $0.20 \mathrm{m}$ from $\mathrm{B}$. How much work will be done in taking $0.02 \mathrm{\mu C}$ of charge from $\mathrm{D}$ to $\mathrm{C}$?