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Q.
A light of wavelength $6000\, \mathring{A} $ in air enters a medium of refractive index $1.5.$ Inside the medium, its frequency is $v$ and its wavelength is $\lambda$. Then,
Wave Optics
Solution:
Given, $\lambda_{ a }=6000\, \mathring{A} $,
$\therefore v_{ a }=\frac{ c }{\lambda_{ a }}$
$=\frac{3 \times 10^{8}}{6000 \times 10^{-10}}$
$=5 \times 10^{14} Hz$
In water, $\lambda_{m}=\frac{\lambda_{ a }}{\mu}=\frac{6000\, \mathring{A} }{1.5}$
$v _{m}= v _{ a }=5 \times 10^{14} Hz$