Two square of sides a and 2a are placed in xy plane with their centers at the origin. Two charges, – q each, are fixed at the vertices of smaller square (lying on X axis). Two charges, Q each, are fixed at the vertices of bigger square on the X axis (see figure). (a) Find work required to slowly move the larger square to infinity from the position shown. (b) Find work done by the external agent in slowly rotating the inner square by `90^(@)` about the Y axis followed by a rotation of `90^(@)` about the Z axis.

Answer

(a). `(8sqrt(2))/(3)(kqQ)/(a)`
(b) `((8sqrt(2))/(3)-(4sqrt(2))/(sqrt(5)))(kqQ)/(a)`