Two concentric conducting shells of radius `a` and `b` `(b gt a)` carry charges `Q` and `-2Q` respectively. The correct variation of electric intensity `E` as a function of `r` is given by

Options

A.
B.
C.
D.

Answer

B

Explanation

The inner face of the outer shell has the charge `-Q` and its outer face also has the charge `-Q`

The final charge distribution on each face of shells shpwn in figure. The expression for electric field given by `E=(kQ)/(r^(2))` for `a lt r lt b` (radially outward)
And `E= -(kQ)/(r^(2))` for `r gt b` (radially inwards)
Note that the field in the outward direction is assumed to be positive.