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 center of `A and B`. Study the following statements.
(i) The potential at a distance `r` from `C`, where
`a le r le b, is (1)/(4 pi epsilon_0)(q/( r))`
(ii) The potential difference between `A and B` is
`(1)/(4 pi epsilon_0) Q ((1)/( a) - (1)/B)`
(iii) The potential at a distance `r` from `C`, where
`a le r le b, is (1)/(4 pi epsilon_0) Q ((1)/r - (1)/B)`
Which of the following statements are correct ?
.

Options

A. `{:(P,Q,R,S),(3,1,2,4):}`
B. `{:(P,Q,R,S),(1,2,3,4):}`
C. `{:(P,Q,R,S),(2,3,4,1):}`
D. `{:(P,Q,R,S),(3,4,1,2):}`

Explanation

Field at P is only due to `A=(kQ)/((2)^(2))=(kQ)/(4)`
Potential at `P=V_("due to A")+V_("due to B")=(kQ)/(2)-(kQ)/(3)`
electric field outside B is due to A s lnduced charge on B+a's charge = zero.