Physics - Geometrical Optics Question with Solution | TestHub

The refractive index of a medium is given by, $n=\sqrt{{\mu }_r{\epsilon }_r}$.

For medium $2$, $n_2=\sqrt{1\times 9}=3$

Now speed of light in a medium will be,

$$\begin{gathered} \frac{c}{v}=n \\ \Rightarrow v=\frac{3\times {10}^8}{3}=1\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1} \end{gathered}$$