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

Answer

d

Explanation

Let the charge on the smaller sphere be `q`. As the potential of both will be the same finally,
`q/(r') = (Q - q)/( r)` or `q = (Q r')/(r + r')`.