Find the dispersion produced by a thin prism of 18° having refractive index for red light = 1.56 and for violet light = 1.68.
Answer & explanation
Correct answer: option 3
We know that dispersion produced by a thin prism
$θ=(μ_v-μ_R)A$
Here $μ_v= 1.68, μ_R = 1.56$ and A = 18°.
$θ = (1.68 − 1.56) × 18° = 2.16°$