question_answer

A solid sphereical conductor of radius R has a spherical cavity of radius a \[(a<R)\] at its centre. A charge \[+Q\] is kept at the centre. The cahrge at the inner surface, outer and at a position \[r(a<r<R)\] are respectively

A) \[+Q,-Q,0\]           

B) \[-Q,+Q,0\]

C) \[0,-Q,0\]              

D)  \[+Q,0,0\]

Correct Answer: B

Solution :

The charge at the inner surface, outer surface and inside the conductor at \[P=(-Q,+Q,0)\] as shown in the figure