Question

Let V and E represent the gravitational potential and field at a distance r from the centre of a uniform solid sphere. Consider the two statements:
(A) the plot of V against r is discontinuous.
(B) The plot of E against r is discontinuous.
(a) Both A and B are correct.
(b) A is correct but B is wrong.
(c) B is correct but A is wrong.
(d) Both A and B are wrong.

Answer 1

(d) Both A and B are wrong.

EXPLANATION: 

(A) is wrong because the value of V at the center is -3GM/2a and it increases continuously to -GM/a at the surface and from -GM/a at the surface to zero at the infinity. So it is continuous.          

(B) is wrong because the value of E increases linearly from zero at the center to GM/a² at the surface, then decreases from GM/a² at the surface to zero at the infinity. So it is also continuous.