A conducting sphere `A` of radius `a` ,with charge `Q` , is placed concentrically inside a conducting shell `B` of radius `b` . `B` is earthed. `C` is the common centre of the `A` and `B`
A. The field at a distance `r` form `C` where `alerleb` is `(1)/(4piepsilon_(0))(Q)/(r^(2))`
B. The potential at a distance `r` form `C` where `a lt rlt b` is `(1)/(4piepsilon_(0))(Q)/(r )`
C. The potential difference between `A` and `B` is `(1)/(4piepsilon_(0))(Q)((1)/(a)-(1)/(b))`
D. The potentia at a distance `r` from `C` where `a le r le b` is ,`(1)/(4piepsilon_(0))Q((1)/(r )-(1)/(b))`
