What is the relationship between refraction and frequency?

"The index of refraction of any material (besides vacuum) varies slightly with the frequency of light: the higher the frequency, the greater the index of refraction. Since red light has a lower frequency than violet, its index of refraction will be lower.

What happens to the frequency of light when it is refracted?

When refracting, light doesn't change its frequency, but since it changes its speed, it must also change its wavelength. When light undergoes refraction, its frequency remains the same. Note: In refraction of light waves, as waves travel from rarer medium into the denser medium, they slow down and wavelength decreases.