Physics 1220 In-Class Problems: Refraction

1. A ray of light is incident at 35.0° on a 5.00 mm thick plane of glass with refractive index n = 1.70. What is the displacement of the ray?
   

2. A beam of sunlight encounters a plate of crown glass at an angle of 45.00°. If the index of refraction for red light in crown glass is n_r = 1.520 and for violet light is n_v = 1.538, find the angle between the violet ray and the red ray in the glass.
   
   

3. A beam of light is incident at an angle θ = 40.0° on a triangular prism of angle α = 45.0° and index n = 1.50 as shown below. Find the angle β at which it emerges.
   

4. To determine the refractive index of a transparent material, its critical angle is measured in air. If θ_c = 40.5°, what is the index of refraction of the solid?
   

5. A point source of light is submerged 2.2 m below the surface of a lake and emits rays in all directions. On the surface of the lake, directly above the source, the area illuminated is a circle. What is the maximum radius that this circle could have?
   

6. A silver medallion is sealed within a transparent block of plastic. An observer in air , viewing the medallion from directly above, sees the medallion at an apparent depth of 1.6 cm beneath the top surface of the medallion. How far below the top surface would the medallion appear if the observer (not wearing goggles) and the block were under water?
   

7. In the diagram below, parallel layers of air, water (n_w = 1.33), and glass (n_g = 1.20) are shown. A ray is incident from air at an angle θ, refracted in the water, and reflected off the glass. That reflected light is completely polarized. What is the angle of incidence θ?
   
   

8. A beam of light of intensity I₀ encounters two polarizers. The transmission axis of the first polarizer is tilted at 25 to the vertical. The transmission axis of the second polarizer is tilted at 55 to the vertical. Find the intensity of the light after it passes through both polarizers if the light is initially
   (a) unpolarized,
   (b) polarized vertically,
   (c) polarized horizontally.
   
   

Questions? mike.coombes@kwantlen.ca