10. Dispersion Of Light

Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. The dispersion of white light occurs because different colours of light bend through different angles with respect to the incident ray, as they pass through a prism. Upon passage through the prism, the white light is separated into its component colours such as the VIBGYOR or the rainbow pattern. This separation of visible light into its different colours after passing through a prism is known as the Dispersion of light. 

Dispersion of white light into seven colours occurs because the light of different colours has different wavelengths. Lights of all colours travel at same speed in vacuum. But in any other transparent medium, lights of different colours travel at different speeds. Due to differences in their speed, lights of different colours bends at different angles. In this band of seven colours, red light has the longest wavelength and violet has the shortest. In any transparent medium, red light travels at the fastest speed whereas violet travels at the lowest. Hence, red light bends the least and violet light bends the most. Rainbow is an example for the dispersion of light.