When the white light is incident on the refracting face of the prism:
1. red waves undergo least deviation
2. waves with longer wavelength deviate lesser
3. the phenomenon of differential deviation of rays is called dispersion
Which among the above statements is / are correct?

Answer: [D] Only 1 & 3

The phenomenon due to which white light splits up into seven colours on passing through a prism is called dispersion of light. White light is made of seven colour bands (VIBGYOR), such that the rays in each band have different wavelength and different frequencies. When the white light is incident on the refracting face of the prism each coloured ray deviates through different angle, depending upon its wavelength. The red rays deviate least, whereas the violet rays deviate most. It is this differential deviation of rays, which causes dispersion. Violet colour deviates the most.

This question is a part of GKToday's Integrated IAS General Studies Module