Total Internal Reflection: an Optic Fiber Is Made of Clear

Multiple Choice

Total internal reflection: An optic fiber is made of clear plastic with index of refraction of 1.50, surrounded by air. For what angles of incidence θ will light remain within the plastic fiber?

A) θ ≥ 21.1°
B) θ < 38.3°
C) θ > 38.3°
D) θ < 41.8°
E) θ > 41.8°