On rotating a point charge having a charge $q$ around a charge $Q$ in a circle of radius $r$,the work done will be:

There is $10$ units of charge at the centre of a circle of radius $10\,m$. The work done in moving $1\,unit$ of charge around the circle once is...........$units$.

What is an equipotential surface? Draw equipotential surfaces for:
$(1)$ $A$ single point charge
$(2)$ $A$ dipole (charges $+q$ and $-q$ at a small distance)
$(3)$ Two $+q$ charges at a small distance
$(4)$ $A$ uniform electric field.

The angle between an equipotential surface and the electric lines of force is .......$^o$.

Positive and negative point charges of equal magnitude are kept at $(0, 0, a/2)$ and $(0, 0, -a/2)$,respectively. The work done by the electric field when another positive point charge is moved from $(-a, 0, 0)$ to $(0, a, 0)$ is

Which of the following figures shows the correct equipotential surfaces of a system of two positive charges?