Q. A point mass $m$ is placed inside a spherical shell of radius $R$ and mass $M$. at a distance $R/2$ from the centre of the shell. The gravitational force exerted by the shell on the point mass is
A) $\frac{GMm}{R^{2}}$
B) $- \frac{GMm}{R^{2}}$
C) Zero
D) $4\frac{GMm}{R^{2}}$
Explanation
(c) Gravitational field due to a spherical shell
At a point inside the shell, $i.e.,\ r < R$
$E_{inside} = 0$
$\therefore$ The gravitational force acting on a point mass $m$ at a distance $R/2$ is
$F = mE_{inside} = 0$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.