How does a glass prism separate white light into colours?

A glass prism separates white light into its constituent colours through a phenomenon known as dispersion.

When white light enters a prism, it undergoes refraction, or bending, as it moves from the air into the glass. Because the refractive index of the glass varies depending on the wavelength of the light, each component colour is bent by a different amount.12

Specifically, shorter wavelengths—those toward the violet end of the spectrum—are refracted the most, while longer wavelengths toward the red end are refracted the least. This differential bending causes the white light to fan out into a continuous band of colours. This process, which was famously demonstrated by Isaac Newton, illustrates that white light is composed of a range of wavelengths, each corresponding to a specific colour.314