Wave Optics – Solutions

1) Monochromatic light of wavelength 589 nm is incident from air on a water surface. What are the wavelength, frequency and speed of (a) reflected and (b) refracted light? The refractive index of water is 1.33.

Solution:

(a) For reflected wave (light): the wavelength will remain unchanged.

According to the question:

Wavelength of incident wave, λ = 589 nm = 589 x 10^-9 m

Speed of light in air, c = 3 x 10⁸ m s^-1

Since c = vλ, where v is the frequency of light

v = c/λ = /589 x 10^-9

v = 3/589 x 10¹⁷ = 5.09 x 10¹⁴ Hz