Q. If $c$ is the speed of electromagnetic waves in vacuum, its speed in a medium of dielectric constant $K$ and relative permeability $\mu_{r}$ is
A) $v = \frac{1}{\sqrt{\mu_{r}K}}$
B) $v = c\sqrt{\mu_{r}K}$
C) $v = \frac{c}{\sqrt{\mu_{r}K}}$
D) $v = \frac{K}{\sqrt{\mu_{r}C}}$
Explanation
(c) Speed of light of vacuum $c = \frac{1}{\sqrt{\mu_{0}\varepsilon_{0}}}$ and in another medium $v = \frac{1}{\sqrt{\mu\varepsilon}}$
$\therefore\frac{c}{v} = \sqrt{\frac{\mu\varepsilon}{\mu_{0}\varepsilon_{0}}} = \sqrt{\mu_{r}K} \Rightarrow v = \frac{c}{\sqrt{\mu_{r}K}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.