A charge Q id distributed over two concentric netal shells of radii r and `R( gt r)` such of the two shells are equal . The charge density of the inner sphere is

Options

A. `Q/(4pir^(2))`
B. `Q/(4piR^(2))`
C. `Q/(4pi(R^(2)+r^(2)))`
D. `Q/(4pi(R^(2)-r^(2)))`

Answer

B

Explanation

`sigma_(1) = sigma_(2)`
` rArr q/(4pir^(2)) = Q/(4piR^(2))`
`rArr " " q = Q(r^(2))/(R^(2))`

` :. " " sigma_(1) = q/(4pir^(2)) = (Qr^(2))/(R^(2)) xx1/(4pir^(2)) = Q/(4piR^(2))`