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 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.
   

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

4. 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?
   

5. 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?
   

6. If you are not looking directly from above, the apparent depth equation will not work. Instead you need to do the geometry. If a person on the side of a pool sees a pair of googles at the bottom of a swimming pool (known to be 1.8 m deep) at an angle from normal of 40°, what does the person think the depth of the pool to be? What value would you get from the apparent depth formula?
   

7. 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 as they emerge the glass. The diagram below is for a ray of a single colour. You need to find the difference in β for the two indices.
   
   

Questions? mike.coombes@kpu.ca