Write a short answer to each question. 30. State the law of reflection. (9.1) ku 31. Identify the factors that determine the frequency of a wave. (9.1) kru 32. How does the speed of a light wave vary with the index of refraction? (9.2) ku 33. Define the node and nodal line. (9.3) ku 34. A dam with a small opening is placed in a ripple tank. The water waves have a wavelength of 4 cm. What size of opening will produce the largest diffraction: a 1 cm opening, an 8 cm opening, or a 20 cm opening? Explain your answer. (9.3) Kru 35. A wave encounters a barrier that has an opening that is similar in size to the wavelength. What happens to the wave? (9.3) kru 36. Identify the quantities that determine the amount of diffraction of a light wave due to a single slit. (9.3) ku 37. Describe what happens to the spacing of nodal lines in a ripple tank with two sources when the source separation increases. (9.3) u T 38. How did Newton explain refraction in his particle (corpuscular) theory of light? (9.4) kru 39. Which model of light would you expect to better explain polarization: the corpuscular model or the wave model? Explain your answer. (9.4, 10.5) 40. Summarize Huygens' principle in your own words. (9.4) AUG 41. Identify two obstacles that challenged early attempts to show light interference. (9.5) kru