Question

The work done in carrying a charge q once round a circle of radius a with a charge Q at its centre is:

• A. $\frac{qQ}{4\pi {\epsilon }_{0}a}$
• B. $\frac{qQ}{4\pi {\epsilon }_0{a}^2}$
• C. $\frac{q}{4\pi {\epsilon }_{0}a}$
• D. zero

Answer 1

The correct option is D zero

The electric potential at any point on circle of radius $a$ due to charge $Q$ at its centre is
$V=\frac{1}{4\pi {\epsilon }_0}\frac{Q}{a}$
It is an equipotential surface.
Hence, work done is carrying a charge $q$ round the circle is zero