question_answer

A square of side ?a? has charge Q at its centre and charge ?q? at one of the corners. The work required to be done in moving the charge ?q? from the corner to the diagonally opposite corner is                                           [UPSEAT 2004]

A)            Zero

B)            \[\frac{Qq}{4\pi {{\in }_{0}}a}\]

C)                    \[\frac{Qq\sqrt{2}}{4\pi {{\in }_{0}}a}\]

D)                                      \[\frac{Qq}{2\pi {{\in }_{0}}a}\]

Correct Answer: A

Solution :

                     From symmetry of the figure all corner have same electric potential. Therefore work done in moving the charge q from the corner to the diagonally opposite corner is zero.