A light ray is propagating in water. Find the critical angle for the ray incident on an interface between air and water. Use a value of 1.33 for the refractive index of water.
Find the critical angle for a light ray propagating in the core of an optical fiber. The ray is incident on the interface between the core and the cladding of the fiber. The core consists of plastic with a refractive index of 1.48 and the cladding consists of plastic with a refractive index of 1.44.
You are using total internal reflection to make a corner reflector. The reflector is in air and the incident angle of light on the reflector is from its surface. What must the minimum index of refraction of the material from which the reflector is made be?