Q. The ratio of the forces between two small spheres with constant charge $(a)$ in air $(b)$ in a medium of dielectric constant $K$ is
A) $1\ :K$
B) $K\ :1$
C) $1\ :K^{2}$
D) $K^{2}:1$
Explanation
(b) $F_{a} = \ \frac{q_{1}q_{2}}{4\pi\varepsilon_{0}r^{2}},\ F_{b} = \frac{q_{1}q_{2}}{K4\pi\varepsilon_{0}r^{2}} \Rightarrow F_{a}\ :F_{b} = K:1$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.