Hi all, I've read that when light undergoes refraction into a medium with higher refractive index it changes speed and this is explained by the electrons of the medium absorbing the photon energy, they hold onto it then eventually re-emit the light if the frequency of light doesn't match the resonant frequency of the medium. The electrons hold onto the energy from light of shorter wavelengths for longer and hence shorter wavelength light slows down more than higher longer wavelengths. What's the physical basis explaining why shorter wavelength light is re-emitted at a slower rate compared to longer wavelengths? The texts I've read don't seem to go into this. Thanks for the help.