Question

A light wave of frequency $5\times {10}^{14}Hz$ enters a medium of refractive index $\mathrm{1.5.}$ In the medium, the velocity of the light wave is .......... and is wavelength is ..........

Answer 1

$c=\upsilon \lambda \lambda =\frac{c}{\upsilon }=\frac{3\times {10}^8}{5\times {10}^{14}}=\frac{3}{5}\times {10}^{-6}$

$\mu =\frac{c}{\upsilon }\Rightarrow 1.5=\frac{3\times {10}^8}{\upsilon }\Rightarrow \upsilon =2\times {10}^8$m/s

$\mu =\frac{{\lambda }_{vaccum}}{{\lambda }_{medium}}\Rightarrow 15=\frac{3}{5}\times \frac{1}{{10}^6}\times \frac{1}{{\lambda }_{medium}}{\lambda }_{medium}=\frac{1}{{10}^7}=1000\mathring{A}$