How does a prism affect white light?

The light is refracted, it changes the angle it is travelling according to the angle of the surface by Snell's law. The index of refraction is continuously different for different wavelengths, so this separates out the wavelengths into a rainbow. read more

Glass slows down light, but the light also keeps a coherent wave-front. So if it hits at an angle it gets refracted. Glass also has a different effect on different wavelengths, so there is some separation of colours. All this happens because the photons hit some of the atoms in the glass, get absorbed and re-admitted. read more

When Light(White Light) enters a prism through one of its face, due to difference in the refractive indexes of the medium i.e. air and the glass of which the prism is made up of, and the difference in the wavelengths of difference colors of which white light is made up of the light scatters and a SPECTRUM of different colors is observed. read more

This causes light of different colors to be refracted differently and to leave the prism at different angles, creating an effect similar to a rainbow. This can be used to separate a beam of white light into its constituent spectrum of colors. A similar separation happens with iridescent materials, such as a soap bubble. read more