An optic fiber is made of clear plastic with index of refraction of 1.50. For what angle of incidence will light remain within the plastic "guide"?
A) 21.1°
B) 23.4°
C) 38.3°
D) 40.3°
E) 41.8°

Question

An optic fiber is made of clear plastic with index of refraction of 1.50. For what angle of incidence will light remain within the plastic "guide"?
A) >21.1°
B) >23.4°
C) >38.3°
D) >40.3°
E) >41.8°

Quizplus · Accepted Answer

The critical angle for total internal reflection can be calculated using the formula: sin(θc) = n2/n1, where n2 is the index of refraction of the surrounding medium (usually air, n2 = 1) and n1 is the index of refraction of the optic fiber (1.50). Solving for θc gives θc = sin^(-1)(1/1.50) ≈ 41.8°. Therefore, for light to remain within the plastic, the angle of incidence must be greater than 41.8°.

An Optic Fiber Is Made of Clear Plastic with Index