A solid metallic sphere has a charge `+3Q`. Concentric with this sphere is a conducting spherical shell having charge `-Q`. The radius of the sphere is `a` and that of the spherical shell is `b(bgta)` What is the electric field at a distance `R(a lt R lt b)` from the centre

Options

A. `(1)/(4pi in_(0)) (Q)/(r )`
B. `(1)/(4pi in_(0)) (3Q)/(r )`
C. `(1)/(4pi in_(0)) (3Q)/(r^(2))`
D. `(1)/(4pi in_(0)) (Q)/(r^(2))`

Answer

C