13.
Monochromatic light of wavelength 600 nm is incident from air to water. What are the wavelength, frequency and speed of (i) reflected, and (ii) refracted light. Refractive index of water is 1.33.
Suggested solution:
(i) Reflected light travels in the same medium (air) as the incident light. Hence, speed of reflected light c = 3 x 108 ms-1. The wavelength (l) of reflected light is 600 nm. The frequency f is
(ii) The refracted rays are in water. Therefore, speed of refracted rays
The frequency of refracted light remains constant when it goes from one medium to other. Hence, f of refracted light is 5 x 1014 Hz. Let l1 be wave length of refracted light. Then,
= 0.4512 x 10-6 = 451.2nm
