A horizontal incident beam consisting of white light passes through an equilater
ID: 2204201 • Letter: A
Question
A horizontal incident beam consisting of white light passes through an equilateral prism, like the one shown in the figure. What is the dispersion (?v - ?r) of the outgoing beam if the prism's index of refraction is nv = 1.495 for violet light and nr = 1.435 for red light?
A horizontal incident beam consisting of white light passes through an equilateral prism, like the one shown in the figure. What is the dispersion (?v - ?r) of the outgoing beam if the prism's index of refraction is nv = 1.495 for violet light and nr = 1.435 for red light?Explanation / Answer
refraction means: sin(a1)=sin(30°)/n =0.5/n, when the white ray enters the prism; angle of incidence on the opposite surface from inside the prism is a2=60° -a1; the angle of exit is a3 =asin(n*sin(a2)) = = asin(n*sin(60 - asin(0.5/n))); ? for violet: a3=74.92°; for red a3=64.29°; d=74.92 – 64.29 =10.63°