The figure below shows the path of a beam of light through several layers (n 1 =
ID: 1262267 • Letter: T
Question
The figure below shows the path of a beam of light through several layers (n1 = 1.59, n2 = 1.38, n3 = 1.18 and n4 = 1.00) of different indices of refraction.
If ?1 = 31.6o, what is the angle, ?2, of the emerging beam?
5.64
Explanation / Answer
nsin theta1 = n2 sin theta 2
1.59 sin 31.6 = 1.38 sin t
t = 37.1 degrees
1.38 sin 37.1 = 1.18 sin t
t = 44.86 degrees
1.18 sin 44.86 = 1 sin t
t = 56.34 degrees
at critical ab gle the refracted ray is at 90 degrees to normal
1.18 sin t = 1 x sin 90
t = 57.93 degrees