Practice!

Sample Problem

The refractive indices of air and water are 1.0 and 1.3, respectively. Under what conditions will total internal reflection occur?

Solution

The light will only have total internal reflection when it goes from a substance of a higher refractive index to one of a lower refractive index, at an angle greater than the critical angle, which is θc = sin-1n2/n1 = 50°.