A small conducing sphere of radius r is lying concentrically inside a bigger hollow conducting sphere of radius R . The bigger and smaller spheres are charged with Q and q `(Qgtq)` and are insulated from each other . The potential difference between the spheres will be

Options

A. `1/(4 pi epsilon_0)(Q/R+q/r)`
B. `1/(4 pi epsilon_0)(q/R-Q/R)`
C. `1/(4 pi epsilon_0)(q/R-Q/r)`
D. `1/(4 pi epsilon_0)(q/r-q/R)`

Answer

D