White light is passed through a prism of angle 5°. If the refractive indices for red and blue colours are 1.641 and 1.659 respectively, calculate the angle of dispersion between them.

Explanation

As for small angle of prism `delta =(mu - 1) A`
`delta_(B )= (1.659-1) xx 5^(@) = 3.295^(@) ` and `delta _(R )`
`= (1.641 -1) xx 5^(@) = 3.205^(@)`
so `theta = delta _(B ) - delta _(R ) = 3.295 ^(@) - 3.205^(@) = 0.090^(@)`