Spherical symmetric charge system centred at origin electric potential `phi = Q/(4piin_(0)R_(0)) r le R_(0)`
`= Q/(4piin_(0)r ) , r R_(0)` :

Options

A. A spherical symmetry at r = `2R_(0)` encloses a net charge Q
B. Electric field is discontinued at `r = R_(0)`
C. Charge is only present at `r = R_(0)`
D. Electrostatic energy is zero for ` r lt R_(0)`

Answer

A, B, C

Explanation

(a,b,c) For `r gt R_(0) E = - (dphi)/(dr) = Q/(4piin_(0) r^(2))`
` :. `Charge enclosed by concentric spherical surface of r
` = 2R_(0) = in_(0) phi_(E ) = in_(0) R 4pi r^(2)`
` = in_(0) Q/(4pi in_(0)r^(2)) 4pir^(2) = Q` For `r lt R_(0), E = - (dV)/(dr) = 0 ` and for `r gt R_(0)`
`E = -(dV)/(dr) = 4piin_(0)r^(2)` (Here `V = phi`)