Ray Optics and Optical Instruments - Result Question 24

24. A beam of monochromatic light is refracted from vacuum into a medium of refractive index 1.5, the wavelength of refracted light will be [1991]

(a) dependent on intensity of refracted light

(b) same

(c) smaller

(d) larger

Show Answer

Answer:

Correct Answer: 24. (c)

Solution:

  1. (c) From $\mu=\frac{c}{v}=\frac{n \lambda_v}{n \lambda_m}, \lambda_m=\frac{\lambda_v}{\mu}$

Here, $c=$ velocity of light in medium and $v=$ velocity of light in vacuum;

$\mu=$ refractive index of the medium.

Hence, wavelength in medium $(\lambda_m)<\lambda_a$ $(\because \mu>1$, given $)$

So, the required wavelength decreases.