Question

A ray of light of wavelength 540 nm traveling in air is incident
on a slab of transparent material. The refractive index of the
material is 1.47. Calculate the wavelength of light in the
material.

Answer 1

The wavelength of light λ in the medium is related with the wavelength of the light in vacuum λ_0 by relationship

λ=λ_0/n

So

λ=(540 nm)/1.47=367 nm