Why does violet light bend more than red light in glass?

Violet light bends more than red light in glass due to a phenomenon known as dispersion. In transparent media like glass, the refractive index is not constant for all wavelengths of light; instead, it varies depending on the light's frequency.12

For visible light, the refractive index of glass increases as the frequency of the light increases. This behavior is called normal dispersion. Because violet light has a higher frequency (and shorter wavelength) than red light, it encounters a higher refractive index when entering the glass. Since the degree of refraction—or the bending of the light ray—is directly dependent on the refractive index, the higher index experienced by violet light causes it to bend more sharply than red light. This separation of white light into its component colors is what allows a prism to create a spectrum.2341