Question

When light propagates through a material medium of relative permittivity $\epsilon_{ r }$ and relative permeability $\mu_{ r ^{\prime}}$ the velocity of light, $v$ is given by : ($c$ - velocity of light in vacuum)

• A. $v=\frac{ c }{\sqrt{\epsilon_{ r } \mu_{ r }}}$
• B. $v= c$
• C. $v=\sqrt{\frac{\mu_{ r }}{\epsilon_{ r }}}$
• D. $v=\sqrt{\frac{\epsilon_{T}}{\mu_{r}}}$

Answer 1

Answer: (A)

$n=\sqrt{\epsilon_{ r } u_{r}}$
$n=\frac{c}{v} \Rightarrow v=\frac{c}{n}$
$v=\left(\frac{c}{\sqrt{\epsilon_{r} \mu_{r}}}\right)$