(a) What is meant by dispersion of white light?
(b) State the colours in the spectrum of white light in ascending order of their wavelengths
(c) Which colour is deviated.
(i) least
(ii) most?
(d) Explain why white light is dispersed when it passes through a glass prism.
(e) Describe, with the aid of a labelled diagram, how a pure spectrum of white light can be produced on a screen.
Explanation
(a) This is the separation of white light into its component or constituent colours.
(b) VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).
(c)(i) Red (ii) Violet.
(d) White light consists of a mixture of different colours. The refractive index of glass is different for each colour so that when white light falls on the prism each colour in it is refracted at different angles with the result that the colours are spread out to form a spectrum
Description: An illuminated slit is placed at the principal focus of a converging lens, such that parallel beam of light emerging therefrom is incident on a prism which disperses the beam into separate parallel beams of different colours each of which is brought into its own focus in the focal plane of a second lens. Here the spectrum is formed on a white screen.