Question

Give reason: a band of colours are produced when white falls on a prism.

Answer 1

All of us are well aware of the dispersion of light that occurs when white light falls on a glass prism. White light is a mixture of seven colours of a rainbow...when it passes through a glass prism the prism disperses the light falling on it and hence produces a band of seven colours.

Answer 2

the white light is the mixture of seven colour in air the velocity or speed of all the colour are same but when the white light enters the glass due the different colours have different speed and wavelength in prism so they get deviated at different angles that is the dispersion of white light into its constituent seven colours takes place at first surface of prism .