The process by which a beam of white light splits into its constituent colours is known as
dispersion
Dispersion is the process by which a beam of white light splits into its constituent colours.
We know that refraction depends on the wavelength of the light. Shorter the wavelength more will be the deviation away from the normal. Among the 7 constituent colours of visible light, violet has the smallest wavelength and hence it deviates the most and red light having the largest wavelength deviates the least as shown in the figure below.
The most common example of dispersion of white light is a rainbow, in which dispersion causes the spatial separation of white light into components of different wavelengths (different colors).