# Why does violet light have a higher refractive index than red light?

Using the equation refractive index = wavelength in a vacuum / wavelength in a substance, wouldn't red light have a higher refractive index?
both violet and red have a shorter wavelength in , for example, water than in vacuum so they both have a refractive index greater than 1... but the question is.... which one has the smaller wavelength compared to each other.
Original post by Mr Naga Physics
both violet and red have a shorter wavelength in , for example, water than in vacuum so they both have a refractive index greater than 1... but the question is.... which one has the smaller wavelength compared to each other.

does that make sense? both have a higher refractive index the more they slow down... but violet slows down more and its wavelength decreases more so it has a higher refractive index than red. This is due to how the violet interacts with matter ( you don't need to learn why, it's to with atomic physics within the substance)