Question #f3082

1 Answer
MM
Apr 14, 2017

61^o

Explanation:

Find the refractive index of the plastic:
n_1 times sin theta_1 = n_2 times sin theta_2

n_1 times sin 30^o = 1 times sin 35^o
n_1 = (sin 35^o)/(sin 30^o) = 1.147

The critical angle is found when the angle of incidence is large enough to make the angle of transmission equal to 90^o.

Therefore, going from plastic to air:
1.147 times sin theta = 1 times sin 90^o
sin theta = 1/1.147
theta = sin^-1 (1/1.147) = 60.7^o

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