Two-point charges $+10 \mu C$ and $-10 \mu C$ are separated by a distance of $2.0 \mathrm{cm}$in air. (i) Calculate the potential energy of the system, assuming the zero of the potential energy to be at infinity. (ii) Draw an equipotential surface of the system.

Two-point charges $A$ and $B$ of values $+15 \mu C$ and $+9 \mu C$ are kept $18 \mathrm{cm}$ apart in the air. Calculate the work done when the charge $B$ is moved by $3 \mathrm{cm}$towards $A$.

Two point charges $20\times {10}^{-6}\mathrm{C}$ and $-4\times {10}^{-6}\mathrm{C}$ are separated by a distance of $50 \mathrm{cm}$ in air. (i)Find the point on the line joining the charges, where the electric potential is zero. (ii) Also, find the electrostatic potential energy of the system.

Two charges, of magnitude $5 nC$and $-2\mathrm{ }\mathrm{nC},$ are placed at points $(2 \mathrm{cm},0,0)$ and $(x \mathrm{cm},0,0)$in a region of space, where there is no other external field. If the electrostatic potential energy of the system is $-0.5 \mu \mathrm{J}$, what is the value of  $x$?

Three-point charges are arranged, as shown in Figure. What is their mutual potential energy? Take $q=1.0\times {10}^{-4}C$ and $a=10 \mathrm{cm}.$

Determine the potential energy of the charge configuration shown in Figure.

Find the amount of work done in arranging the three-point charges, on the vertices of an equilateral triangle $ABC,$of side $10 \mathrm{cm},$as shown in the adjacent figure.

Calculate the work done to dissociate the system of three charges placed on the vertices of a triangle, as shown in Fig. 2.38. Here $q=1.6\times {10}^{-10}C.$

What is the electrostatic potential energy of the charge configuration shown in Figure?

Take $q_1=+ 1.0\times {10}^{-8} \mathrm{C}, q_2=- 2.0\times {10}^{-8}\mathrm{ }\mathrm{C},q_3=+ 3.0\times {10}^{-8} C,q_4=+ 2.0\times {10}^{-8}\mathrm{ }\mathrm{C}$ and $a=1.0$metre.