Question

A positive charge $q$ is placed in a spherical cavity made in a positively charged sphere. The centers of sphere and cavity are displaced by a small distance $\overrightarrow{l}$. Force on charge $q$ is:

• A. In the direction parallel to vector $\overrightarrow{l}$
• B. In radial direction
• C. In the direction perpendicular to vector $\overrightarrow{l}$
• D. Direction cannot be determined

Answer 1

The correct option is A In the direction parallel to vector $\overrightarrow{l}$


Electric field in a cavity
$\overrightarrow{E}=\frac{\rho }{3{ϵ}_0}\overrightarrow{l}$
$\overrightarrow{F}=q\overrightarrow{E}=\frac{q\rho \overrightarrow{l}}{3{ϵ}_0}$