A Fiber Optic Line Is Composed of a Core with an Index

Multiple Choice

A fiber optic line is composed of a core with an index of refraction of 1.51 and cladding with an index of 1.40. Which one of the following relations best describes angles of incidence $\theta$ that will result in total internal reflection within the fiber optic line?

A) $\theta$ < 68°
B) $\theta$ > 68°
C) $\theta$ < 22°
D) $\theta$ > 22°
E) 0 $\le$ $\theta$ $\le$ 90°