Question

Figure, shown below, shows three situations involving a charged particle and a uniformly charged spherical shell. The charges and radii of the shells are indicated in the figure. If $F_{1}, F_{2}$ and $F_{3}$ are the magnitudes of the forces on the particle due to the presence of the shell in situations (I), (II) and (III), respectively, then

• A. $F_{3} > F_{2} > F_{1}$
• B. $F_{2} > F_{2} = F_{3}$
• C. $F_{3} = F_{2} > F_{1}$
• D. $F_{1} > F_{2} > F_{3}$

Answer 1

Answer: (C)

$F_{1}$ is zero as charge lies inside the shell (Electric field inside the shell due to its own charge is zero). $F_{2}=F_{3}$ as charge over the surface of the shell behaves like charge placed at the centre of the shell.