Question

$A$ and $B$ are two concentric spheres If $A$ is given a charge $Q$ while $B$ is earthed as shown in figure :

• A. The charge density of $A$ and $B$ are same
• B. The field inside and outside $A$ is zero
• C. The field between $A$ and $B$ is not zero
• D. The field inside and outside $B$ is zero

Answer 1

The correct option is C The field between $A$ and $B$ is not zero

Given $A$ and $B$ are two concentric spheres. If $A$ is given charge $Q$ while $B$ is earthed, then this arrangement is equivalent to a spherical capacitor. The electric field within the sphere $A$ is zero. Electric field outside the sphere $B$ is also zero.

The electric field between the spheres $A$ and $B$ is non-zero and is given by:

$E=\frac{1}{4\pi {\epsilon }_0}\frac{Q}{r^2}$; i.e, $r$ is the distance from the center and is redirected radially outwards.