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White light propagating in air is incident at 45 degrees on the equilateral pris

ID: 2206078 • Letter: W

Question

White light propagating in air is incident at 45 degrees on the equilateral prism of the figure.

http://session.masteringphysics.com/problemAsset/1036318/4/RW-30-28.jpg

Find the angular dispersion "gamma" of the outgoing beam if the prism has refractive indices nred=1.582 and nviolet= 1.633

ANSWER IN GAMMA DEGREES

I used this expression:


n(air)sin(45) = n(red)*sin(theta(r1)) and n(air)sin(45) = n(violet)sin(theta(v))




Explanation / Answer

n(air)sin(45) = n(red)*sin(theta(r1)) =>1x sin(45) = 1.582 sin(theta 1) => theta 1 = 26.549 degrees since it is a equilateral prism => theta 1 + theta 2 = 60 degrees => theta 2 = 33.45 degrees and 1.582 sin(theta 2) = 1 x sin(gamma 1) => gamma 1 =60.695 degrees similarly for violet n(air)sin(45) = n(violet)*sin(theta(v1)) => 1 x sin(45) = 1.633 sin(theta(v1)) => theta(v1)= 25.658 degrees => theta (v2)= 34.34 degrees => 1.633 x sin(theta(v2)) = 1 x sin(gamma 2) => gamma 2 = 67.1 degrees => gamma = deviation of both of the refracted rays = 6.408 degrees