Question

Light of wavelength 5000 Å propagating in air gets partly reflected from the surface of water. How will the wavelengths and frequencies of the reflected and refracted light be affected?

Answer 1

The frequency and wavelength of reflected wave will not change.

The refracted wave will have same frequency.

The velocity of light in water is given by

v=λf

where
v = Velocity of light

f = Frequency of light

λ = Wavelength of light 

If velocity will decrease, wavelength (λ) will also decrease.