In Figure, two light rays pass from air through five layers of transparent plastic and then back into air. The layers have parallel interfaces and unknown thicknesses; their indexes of refraction are n1 = 1.7, n2 = 1.6, n3 = 1.5, n4 = 1.4, and n5 = 1.6. Ray b is incident at angle ? b = 20?. Relative to a normal at the last interface, at what angle do(a) Ray a and(b) Ray b emerges? If the air at the left and right sides in the figure were, instead, glass with index of refraction 1.5, at what angle would(c) Ray a and(d) Ray b emerges?

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