Two spherical conductors A and B of radii a and b (`b gt a`) are placed concentrically in air. A is given charged +Q while B is earthed. Then the equivalent capacitance of the system is

Options

A. `4piepsi_(0) (ab)/(b-a)`
B. `4piepsi_(0)(a+b)`
C. `4piepsi_(0)b`
D. `4piepsi_(0) a`

Answer

C

Explanation

All the charge given to inner sphere to inner sphere will pass on to the outer one. So capacitance that of outer one is `4pi in_(0) b`.