All GRE Subject Test: Physics Resources
Example Question #7 : Electromagnetics, Waves, And Optics
A beam of light travels through a medium with index of refraction until it reaches an interface with another material, with index of refraction . No light is transmitted into the second material. At what angle (measured from the plane of the interface between the two materials) does the beam hit the second material?
This situation is impossible.
Total internal reflection occurs at the angle:
However, this angle is measured from a line normal to the plane of the interface; the angle we want, therefore, is , which is .