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)/( r) - (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 ?
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Options

A. Only (i) and (ii)
B. Only (ii) and (iii)
C. Only (i) and (iii)
D. All

Answer

b

Explanation

Charge `+Q` will flow into earth.
`V_C = (kQ)/( r) - (kQ)/b`
`V_A = (kQ)/a- (kQ)/b`
Potential at B is zero.
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