Question

The volume charge density of a sphere of radius 6 m is 2μC cm-3. The number of lines of force per unit surface area coming out from the surface of the sphere is _______ × 1010 NC-1.

Answer 1

The number of lines of force per unit surface is nothing but an Electric field at that point
E=ρ$\frac{r}{3}$ϵ0, for r=R
E=ρ$\frac{R}{3}$ϵ0=2×$\frac{6}{3}$×8.85×10-12=0.45×1012 NC-1
=45×1010 N/C