Draw a ray diagram showing the dispersion through a prism when a narrow beam of white light is incident on one of its refracting surfaces. Also,indicate the order of the colours of the spectrum obtained.

(N/A) When a narrow beam of white light is incident on one of the refracting surfaces of a glass prism,it splits into its constituent seven colours. This phenomenon is known as the dispersion of light.
The order of colours in the spectrum obtained,from the base of the prism upwards,is Violet $(V)$,Indigo $(I)$,Blue $(B)$,Green $(G)$,Yellow $(Y)$,Orange $(O)$,and Red $(R)$. This is commonly remembered by the acronym $VIBGYOR$.
Red light bends the least,while violet light bends the most because the refractive index of glass is different for different wavelengths of light.