Question

what is the cause of dispersion of light

Answer 1

Fall of white light through a 3 dimensional prisms splits the white light into 7 colours

Answer 2

Answer:

Dispersion of light is caused by the change of speed of light ray (resulting in angle of deviation) of each wavelength by a different amount. The dispersion of a light wave by a prism is shown in the diagram.  Each color has its own wavelength and frequency, so we see different colors for the same white light.