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`

Options

A. The field at a distance `r` form `C` where `alerleb` is `k(Q)/(r^(2))`
B. the potential at a distance `r` form `C`, where `alerleb` is `k(Q)/(r)`
C. The potential difference between `A` and `B` is `kQ((1)/(a)-(1)/(b))`
D. the potential at a distance `r` from `C` where `alerleb` is `k(Q)((1)/(r)-(1)/(b))`

Answer

3