# Unit 14 Extra Credit

Either print this page and complete or (better yet) neatly show your answers on a separate page of paper. All answers must be expressed as complete sentences and/or all work shown to receive credit

1. A thick sheet of plastic, n=1.500, is used as the side of an aquarium tank. Light reflected from a fish in the water has an angle of incidence of 35.0 degrees. At what angle does the light enter the air?

2. A light source, S, is located 2.0 m below the surface of a swimming pool and 1.5 m from one edge of the pool. The pool is filled to the top with water.

a. At what angle does the light reaching the edge of the pool leave the water?

b. Does this cause the light viewed from this angel to appear deeper or shallower than it actually is?

3. The speed of the light in a clear plastic is 1.90x10^8 m/s. A ray of light enters the plastic at an angle of 22 degrees. At what angle is the ray refracted?

4. How many more minutes would it take light from the sun to reach Earth if the space between them were filled with water rather than a vacuum? The sun is 1.5x10^8 km from Earth.

5. The index of refraction for crown or glass for red light is 1.514, while that for blue light is 1.528. White light is incident on the glass at 30 degrees.

a. Find the angles of refraction for these two colors.

b. Compare the difference in angles to that for diamond found in problem 25.

c. Use the results to explain why diamonds are said to have "fire."

6. Just before sunset, you see a rainbow in the water from a lawn sprinkler. Carefully draw your location and the locations of the sun and the water from the sprinkler that show the rainbow.

Resources for physics students are available through links on the GBS Physics Home Page. Such resources include the Multimedia Physics Studios (a collection of animations and movies which illustrate key physics concepts) and The Physics Classroom (an online tutorial written in an easy-to-understand language).