 By application of Snell's law, one can see that as the wavelength changes, and the refractive index changes, the deflection angle of a light beam will change, separating the colors (wavelength components) of the light spatially.Generally, longer wavelengths (red) thereby undergo a smaller deviation than shorter wavelengths (blue) where the refractive index is larger.A good mathematical description of single-prism dispersion is given by Born and Wolf.