Question

A charged sphere of diameter 4cm has a charge density of 10^-4C/cm². The work done in joules when a charge of 40nano-coulombs is moved from infinite to a point, which is at a distance of 2cm from the surface of the sphere is 

1) 14.4π 

2) 28.8π 

3) 144π 

4) 288π

Answer 1

Correct Option : 1

Explanation :

Work done = potential energy at the given distance r = 2+2 = 4cm from the centre of the sphere.