Unit 52: Reflection & Refraction
Practice Problems
Note: problem difficulty is ranked using a star system.
(*) One-star problems are fundamental to the unit, and can be done relatively quickly. Use these problems to introduce yourself to the material.
(**) Two-star problems are more difficult, and require an understanding of one or two key concepts. Use these problems to test your understanding of the material.
(***) Three-star problems are the most difficult, and require some creative thinking in addition to a deep familiarity with multiple key concepts. Use these problems to challenge yourself; if you can complete one of these, you’re on your way to mastering the material.
*Q52.1) A ray of light passes from air to water as shown below. Find the unknown angles θ and ϕ.
**Q52.2) A thin layer of oil floats atop some water as shown below. Find the unknown angle θ.
**Q52.3) A ray of light enters a glass tube with an index of refraction 1.5 as shown below. The light travels parallel to the upper part of the tube before reflecting off the face AB. Find the largest angle θ for which all the light reflects back into the tube, assuming the tube is surrounded by air.
***Q52.4) A fisherman sits on a dock as shown below. How far above the dock does the top of the fisherman’s head appear to be from the fish’s perspective? Hint: consider the ray shown in red that travels from the top of the fisherman’s head to the fish’s eye.
