Question

Electromagnetic radiation of frequency f, wavelength $\lambda$ and velocity c in air, enters a glass slab of refractive index $\frac{3}{2}$. The frequency, wavelength and velocity of wave in glass slab respectively are.

• A. $f,\frac{2\lambda }{3},\frac{2c}{3}$
• B. $\frac{f}{3},\frac{2\lambda }{3},\frac{3c}{2}$
• C. $\frac{2f}{3},\frac{2\lambda }{3},\frac{2c}{3}$
• D. $f,\lambda ,c$

Answer 1

The correct option is A $f,\frac{2\lambda }{3},\frac{2c}{3}$

The frequency of light wave is independent of medium so $f^{\prime }=f$
The wavelength and velocity of wave in glass medium becomes $\frac{1}{\mu }$ times that in air.
So, ${\lambda }^{\prime }=\frac{\lambda }{\mu }=\frac{\lambda }{3/2}=\frac{2\lambda }{3}$
$c^{\prime }=\frac{c}{\mu }=\frac{2c}{3}$.