CBSE Class 10 Science 2020 · Paper 31/3/1 · Question 24(a)

(a) The incident ray PE bends towards the normal as it enters the prism at E, travels through the glass along EF, and bends away from the normal as it leaves at F, emerging along FS. The emergent ray is bent towards the base of the prism and is deviated from the direction of the incident ray through the angle of deviation $D$. Labels: incident ray, refracted ray, emergent ray, angle of prism $\angle A$, angle of incidence $\angle i$, angle of refraction $\angle r$, angle of emergence $\angle e$, angle of deviation $\angle D$. A monochromatic beam is deviated but does not split. (b) The beam of white light splits into its seven component colours, violet, indigo, blue, green, yellow, orange and red (VIBGYOR), forming a spectrum. This is dispersion: violet is deviated the most and red the least.