Q.

A spherically symmetric charge system is centered at the origin. Given electric potential

V=Q4πε0R0(rR0),  V=Q4πε0r(r>R0).                              [2006]

1 Within r=2R0, total enclosed net charge is Q  
2 Electric field is discontinuous at r=R0  
3 Charge is only present at r=R0  
4 Electrostatic energy is zero for r<R0  

Ans.

(1, 2, 4)

The given V-r graph is of a charged conducting sphere of radius R0

(1)  The whole charge Q will be enclosed in a sphere of diameter 2R0.

(2) Electric field E=0 inside the sphere. Hence electric field is discontinued at r=R0.

(3) Changes in V and E are continuously present for r>R0.

      Option (3) is incorrect.

(4) For r<R0, the potential V is constant and the electric intensity is zero. Obviously the electrostatic energy is zero for r<R0