Q.
A uniformly charged thin spherical shell of radius $R$ carries uniform surface charge density of $\sigma$ per unit area. It is made of two hemispherical shells, held together by pressing them with force $F$ (see figure). $F$ is proportional to
A) $\frac{1}{\varepsilon_{0}}\sigma^{2}R^{2}$
B) $\frac{1}{\varepsilon_{0}}\sigma^{2}R$
C) $\frac{1}{\varepsilon_{0}}\frac{\sigma^{2}}{R}$
D) $\frac{1}{\varepsilon_{0}}\frac{\sigma^{2}}{R^{2}}$
Explanation
(a) Electrostatic repulsive force;
[image:1_image335.emf]
$F_{ele} = \left( \frac{\sigma^{2}}{2\varepsilon_{0}} \right)\pi R^{2};F = F_{ele} = \frac{\sigma^{2}\pi R^{2}}{2\varepsilon_{0}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.