A large insulated sphere of radius r charged with Q units of electricity is placed in contact with a small insulated uncharged sphere of radius r' and is then separated. The charge on the smaller sphere will now be.

Options

A. `Q(r+r')`
B. `Q(r-r')`
C. `(Q)/(r'+r)`
D. `(Qr')/(r'+r)`

Answer

D

Explanation

Common potential, `V=(Q+0)/(4pi epsilon_(0)(r+r'))`
Charge on smaller sphere,
`4pi epsilon_(0)r'xxV=(Qr')/(r+r')`