An Optic Fiber Is Made of Clear Plastic with an Index

Multiple Choice

An optic fiber is made of clear plastic with an index of refraction of 1.50.For what range of angles of incidence θ with the lateral surface of the fiber will light remain inside the plastic "guide" if it is surrounded by air?

A) 21.1° < θ < 90°
B) 23.4° < θ < 90°
C) 38.3° < θ < 90°
D) 40.3° < θ < 90°
E) 41.8° < θ < 90°