For a transparent medium, the relative permeability and permittivity, ${\mu }_r$ and ${\epsilon }_r$ are $1.0$ and $1.44$ respectively. The velocity of light in this medium would be:

Given, relative permittivity, ${\epsilon }_r=1.44$ and relative permeability, ${\mu }_r=1$

Now, as we know that, $\epsilon ={\epsilon }_r{\epsilon }_0$ and $\mu ={\mu }_r{\mu }_0$

$\therefore$ Velocity of light in medium will be,

$v=\frac{1}{\sqrt{\mu \epsilon }}=\frac{1}{\sqrt{{\mu }_r{\mu }_0{\epsilon }_r{\epsilon }_0}}=\frac{c}{\sqrt{{\mu }_r{\epsilon }_r}}=\frac{3\times {10}^8}{\sqrt{1\times 1.44}}=2.5\times {10}^8 \mathrm{m}/\mathrm{s}$