A Beam of Light, Traveling in Air, Strikes a Plate

Multiple Choice

A beam of light, traveling in air, strikes a plate of transparent material at an angle of incidence of 56°. It is observed that the reflected and refracted beams form an angle of 90°. What is the index of refraction of this material?

A) n = 1.44
B) n = 1.53
C) n = 1.48
D) n = 1.40
E) n = 1.43