What is visible spectrum

Human Eye & Colourful World (C10)

(i) What is visible spectrum?

(ii) Why is red used as the stopping light at traffic signals?

(iii) Two triangular glass prisms are kept together connected through their rectangular side. A light beam is passed through one side of the combination. Will there be any dispersion? Justify your answer.

Answer

(i) Visible spectrum is the band of coloured components of a white light beam.

(ii) Red light is scattered the least by air molecules and has longer wavelength. It travels the longest distance.

(iii) The given setup will behave like a glass slab, resulting in recombination of the seven colours to produce white light.