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
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Answer:
Correct Answer: 24. (c)
Solution:
- (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.
