Question

The region between two concentric spheres of radii $'a'$ and $'b'$, respectively (see figure), has volume charge density $\rho = \frac{A}{r}$, where $A$ is a constant and $r$ is the distance from the centre. At the centre of the spheres is a point charge $Q$. The value of $A$ such that the electric field in the region between the spheres will be constant, is :

• A. $\frac{Q}{2 \pi a^2}$
• B. $\frac{Q}{2 \pi (b^2 - a^2)}$
• C. $\frac{Q}{ \pi (a^2 - b^2)}$
• D. $\frac{2 Q}{\pi a^2}$

Answer 1

Answer: (A)

$\frac{Q}{2 \pi a^2}$

Answer 2