Question

What is the connection between wavelength and refractive index?​

Answer 1

The refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is v = c/n, and similarly the wavelength in that medium is λ = λ0/n, where λ0 is the wavelength of that light in vacuum.

Answer 2

The refractive index is related to the wavelength by substituting the velocity formula. The wavelength of the light changes according to the density of the medium and frequency remains same irrespective of the medium. So, the refractive index of light depends only on the wavelength, not on the frequency.