Question

A light of wavelength $6000\stackrel{\circ }{A}$, in air, enters a medium with refractive index $1.5$. Inside the medium, its frequency is ________ $Hz$ and its wavelength is _______ $\stackrel{\circ }{A}$.

Answer 1

Frequency remains the same, i.e.,
$f=\frac{c}{\lambda }=\frac{3\times {10}^8}{6000\times {10}^{-10}}=5\times {10}^{14}Hz$
$\mu =\frac{V_1}{V_2}=\frac{v{\lambda }_1}{v{\lambda }_2}\Rightarrow ={\lambda }_2=\frac{{\lambda }_1}{\mu }$
The wavelength gets modified to
${\lambda }_2=\frac{{\lambda }_1}{\mu }=\frac{6000\stackrel{\circ }{A}}{1.5}=4000\stackrel{\circ }{A}$.