# Why is refraction of light at a boundary wavelength dependent, and are the two proportional? [duplicate]

Just wondering, why is it that blue light will refract less than red light, i.e. why does the fact that blue light has a shorter wavelength mean that it will refract less at a boundary?

I read somewhere that the wavelength decreases of light as it enters an optically denser material, which seems logical given that frequency remains constant and c = f λ. Is there some sort of constant which would mean that if the wavelength of a type of light in material one is x% shorter than that of, say, red light, the wavelength after refraction would be kx% shorter?

I know this is a terribly worded question, this is all new to me and it's a bit difficult for me to put down my thought process.

• There's a lot buried underneath the surface of your question. I'll point out that the constant you are looking for is the index of refraction defined as $n=c/v$ where $v$ is the speed of light in the medium. With that, $\lambda_{in} = \lambda_{out}/n$. The value of $n$ (or $v$) depends in a complicated way on the arrangement of atoms/molecules in the system, and the properties of those atoms/molecules. Maybe you can take it from there. – garyp Jul 14 '20 at 11:53