A thin walled spherical conducting shells `S` of radius `R` is given charge `Q`,the same amount of charge is also placed at its centre `C`.Which of the following statements are correct.

Options

A. On the outer surface of S, the charge density is `Q//2piR^2`.
B. The electric field is zero at all points inside S.
C. At a point just outside S, the electric field is double the field at a point just inside S in the cavity.
D. At any point inside S (i.e., within its cavity), the electric field is inversely proportional to the square of its distance from C.

Answer

A, C, D

Explanation

a.,c.,d.
Charge density at the outer surface (Fig. SAI.59) is
`(2Q)/(4piR^(2))=(Q)/(2piR^(2))`
`E_("inside")=(Q)/(4piepsilon_(0)R^(2)),E_("outside")=(2Q)/(4piepsilon_(0)R^(2))`
`therefore E_("outside")=2E_("inside")`