In Fig. 35-34, a light ray is incident at angle 1 = 50 on a series of five transparent layers with parallel boundaries. For layers

In Fig. 35-34, a light ray is incident at angle θ1 = 50° on a series of five transparent layers with parallel boundaries. For layers 1 and 3, L1 = 20 mm, L3 = 25 mm, n1 = 1.6, and n3 =1.45.
(a) At what angle does the light emerge back into air at the right?
(b) How much time does the light take to travel through layer 3?

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