Question

The wavelengths of a certain light in air and in a medium are 4560 Å and 3648 Å, respectively. Compare the speed of light in air with its speed in the medium.

Answer 1

Let v_a and v_m be the speeds of light in air and in the medium respectively and let λ_a and λ_m  be the wavelengths of light in air and in the medium respectively. Let v be the frequency of light in air.

When light passes from one medium to another, its frequency remains unchanged.