Question

A conducting sphere of radius R, and carrying a charge q is joined to a conducting sphere of radius 2R, and carrying a charge – 2q. The charge flown between them will be?

• A. $\frac{q}{3}$
• B. $\frac{2q}{3}$
• C. $q$
• D. $\frac{4q}{3}$

Answer 1

The correct option is D $\frac{4q}{3}$

Initial charge on sphere of radius R = q
Charge on this sphere after joining $=q^{\prime }=\frac{Rq+(-2q)\times R}{R+2R}=\frac{-q\times R}{3R}=\frac{-q}{3}$
So charge flown between them $=q-(-\frac{q}{3})=\frac{4q}{3}$