1. Christian Huygens Dutch Physicist and Astronomer (1629–1695) Huygens is best known for his contributions to the fields of optics and dynamics. To Huygens, light was a type of vibratory motion, spreading out and producing the sensation of light when impinging on the eye. On the basis of this theory, he deduced the laws of reflection and refraction and explained the phenomenon of double refraction. (Courtesy of Rijksmuseum voor de Geschiedenis der Natuurwetenschappen and Niels Bohr Library.)
p.1108

2. Fig 35-CO This photograph of a rainbow shows a distinct secondary rainbow with the colors reversed. The appearance of the rainbow depends on three optical phenomena discussed in this chapter—reflection, refraction, and dispersion. (Mark D. Phillips/Photo Researchers, Inc.)
Fig 35-CO, p.1095

3. Figure 34. 12 The electromagnetic spectrum
Figure The electromagnetic spectrum. Note the overlap between adjacent wave types. The expanded view to the right shows details of the visible spectrum.
Fig 34-12, p.1081

4. Active Figure 34.3 Representation of a sinusoidal, linearly polarized plane electromagnetic wave moving in the positive x direction with velocity c. (a) The wave at some instant. Note the sinusoidal variations of E and B with x.
Fig 34-3a, p.1071

5. Figure 35.5 Schematic representation of (a) specular reflection, where the reflected rays are all parallel to each other, and (b) diffuse reflection, where the reflected rays travel in random directions.
Fig 35-5ab, p.1098

6. Figure 35.13 Overhead view of a barrel rolling from concrete onto grass.
Fig 35-13, p.1104

7. Table 35-1, p.1104

8. Figure As a wave moves from medium 1 to medium 2, its wavelength changes but its frequency remains constant.
Fig 35-14, p.1104

9. Active Figure (a) Rays travel from a medium of index of refraction n1 into a medium of index of refraction n2, where n2 < n1. As the angle of incidence 1 increases, the angle of refraction 2 increases until 2 is 90° (ray 4). For even larger angles of incidence, total internal reflection occurs (ray 5).
Fig 35-26a, p.1112

10. (Left ) Strands of glass optical fibers are used to carry voice, video, and data signals in telecommunication networks.
p.1114

11. Figure 35.29 Light travels in a curved transparent rod by multiple internal reflections.
Fig 35-29, p.1114

12. A bundle of optical fibers is illuminated by a laser.

13. Figure 35. 30 The construction of an optical fiber
Figure The construction of an optical fiber. Light travels in the core, which is surrounded by a cladding and a protective jacket.
Fig 35-30, p.1114

14. Figure 35.20 Variation of index of refraction with vacuum wavelength for three materials.
Fig 35-20, p.1109

15. Figure 35.24 The formation of a rainbow seen by an observer standing with the Sun behind his back.
Fig 35-24, p.1110

16. Figure 35. 22 White light enters a glass prism at the upper left
Figure White light enters a glass prism at the upper left. A reflected beam of light comes out of the prism just below the incoming beam. The beam moving toward the lower right shows distinct colors. Different colors are refracted at different angles because the index of refraction of the glass depends on wavelength. Violet light deviates the most; red light deviates the least.
Fig 35-22, p.1110

17. Figure 35.21 A prism refracts a single-wavelength light ray through an angle  .
Fig 35-21, p.1109

18. Figure 35.7 (Example 35.2) (b) The geometry for an arbitrary mirror angle.
Fig 35-7b, p.1100

19. Figure 35. 8 Applications of retroreflection
Figure 35.8 Applications of retroreflection. (a) This panel on the Moon reflects a laser beam directly back to its source on the Earth. (b) An automobile taillight has small retroreflectors that ensure that headlight beams are reflected back toward the car that sent them. (c) A light ray hitting a transparent sphere at the proper position is retroreflected. (d) This stop sign appears to glow in headlight beams because its surface is covered with a layer of many tiny retroreflecting spheres. What would you see if the sign had a mirror-like surface?
Fig 35-8, p.1101

20. Active Figure (a) A ray obliquely incident on an air–glass interface. The refracted ray is bent toward the normal because v2 < v1. All rays and the normal lie in the same plane. (b) Light incident on the Lucite block bends both when it enters the block and when it leaves the block.
Fig 35-10, p.1102

21. Active Figure (a) When the light beam moves from air into glass, the light slows down on entering the glass and its path is bent toward the normal. (b) When the beam moves from glass into air, the light speeds up on entering the air and its path is bent away from the normal.
Fig 35-11, p.1103

22. Active Figure 35.4 A plane wave of wavelength  is incident on a barrier in which there is an opening of diameter d. (a) When  << d, the rays continue in a straightline path, and the ray approximation remains valid. (b) When   d, the rays spread out after passing through the opening. (c) When  >> d, the opening behaves as a point source emitting spherical waves.
Fig 35-4, p.1098

23. Active Figure 35.4 A plane wave of wavelength  is incident on a barrier in which there is an opening of diameter d. (a) When  << d, the rays continue in a straightline path, and the ray approximation remains valid.
Fig 35-4a, p.1098

24. Active Figure 35.4 A plane wave of wavelength  is incident on a barrier in which there is an opening of diameter d. (b) When   d, the rays spread out after passing through the opening.
Fig 35-4b, p.1098

25. Active Figure 35.4 A plane wave of wavelength  is incident on a barrier in which there is an opening of diameter d. (c) When  >> d, the opening behaves as a point source emitting spherical waves.
Fig 35-4c, p.1098

26. Active Figure 35. 23 Path of sunlight through a spherical raindrop
Active Figure Path of sunlight through a spherical raindrop. Light following this path contributes to the visible rainbow.
Fig 35-23, p.1110

27. Figure (a) Huygens’s construction for proving the law of reflection. At the instant that ray 1 strikes the surface, it sends out a Huygens wavelet from A and ray 2 sends out a Huygens wavelet from B. We choose a radius of the wavelet to be c  t, where  t is the time interval for ray 2 to travel from B to C. (b) Triangle ADC is congruent to triangle ABC.
Fig 35-18, p.1108

28. Figure (a) Huygens’s construction for proving the law of reflection. At the instant that ray 1 strikes the surface, it sends out a Huygens wavelet from A and ray 2 sends out a Huygens wavelet from B. We choose a radius of the wavelet to be c  t, where  t is the time interval for ray 2 to travel from B to C.
Fig 35-18a, p.1108

29. Figure 35.18 (b) Triangle ADC is congruent to triangle ABC.
Fig 35-18b, p.1108

30. Figure Huygens’s construction for proving Snell’s law of refraction. At the instant that ray 1 strikes the surface, it sends out a Huygens wavelet from A and ray 2 sends out a Huygens wavelet from B. The two wavelets have different radii because they travel in different media.
Fig 35-19, p.1109

31. Figure (Example 35.7) A light ray passing through a prism at the minimum angle of deviation  min.
Fig 35-25, p.1111

32. Active Figure (a) Rays travel from a medium of index of refraction n1 into a medium of index of refraction n2, where n2 < n1. As the angle of incidence 1 increases, the angle of refraction 2 increases until 2 is 90° (ray 4). For even larger angles of incidence, total internal reflection occurs (ray 5). (b) The angle of incidence producing an angle of refraction equal to 90° is the critical angle c. At this angle of incidence, all of the energy of the incident light is reflected.
Fig 35-26, p.1112

33. Active Figure (b) The angle of incidence producing an angle of refraction equal to 90° is the critical angle c. At this angle of incidence, all of the energy of the incident light is reflected.
Fig 35-26b, p.1112

34. Figure (Quick Quiz 35.6 and 35.7) Five nonparallel light rays enter a glass prism from the left.
Fig 35-27, p.1113

35. Figure 35.28 (Example 35.8) A fish looks upward toward the water surface.
Fig 35-28, p.1113

36. Figure 35.31 Geometry for deriving Snell’s law of refraction using Fermat’s principle.
Fig 35-31, p.1115

37. Fig Q35-6a, p.1117

38. Fig Q35-6b, p.1117

39. Fig Q35-17, p.1117

40. Fig P35-4, p.1118

41. Fig P35-6, p.1118

42. Fig P35-8, p.1119

43. Fig P35-21, p.1119

44. Fig P35-23, p.1120

45. Fig P35-27, p.1120

46. Fig P35-28, p.1120

47. Fig P35-33, p.1121

48. Fig P35-35, p.1121

49. Fig P35-38, p.1121

50. Fig P35-40, p.1121

51. Fig P35-43, p.1122

52. Fig P35-45, p.1122

53. Fig P35-50, p.1122

54. Fig P35-52, p.1123

55. Fig P35-55, p.1123

56. Fig P35-59, p.1123

57. Fig P35-61, p.1124

58. Fig P35-63, p.1124

59. Fig P35-66, p.1124

60. Fig P35-67, p.1124

61. Fig P35-69, p.1124

62. Fig P35-70, p.1125

63. Fig P35-71, p.1125

64. Figure 35. 1 Roemer’s method for measuring the speed of light
Figure 35.1 Roemer’s method for measuring the speed of light. In the time interval during which the Earth travels 90° around the Sun (three months), Jupiter travels only about 7.5° (drawing not to scale).
Fig 35-1, p.1096

65. Figure 35.2 Fizeau’s method for measuring the speed of light using a rotating toothed wheel. The light source is considered to be at the location of the wheel; thus, the distance d is known.
Fig 35-2, p.1097

66. Figure 35. 3 A plane wave propagating to the right
Figure 35.3 A plane wave propagating to the right. Note that the rays, which always point in the direction of the wave propagation, are straight lines perpendicular to the wave fronts.
Fig 35-3, p.1097

67. Figure 35.5 Schematic representation of (a) specular reflection, where the reflected rays are all parallel to each other
Fig 35-5a, p.1098

68. Figure 35.5 Schematic representation of (b) diffuse reflection, where the reflected rays travel in random directions.
Fig 35-5b, p.1098

69. Figure 35.5 (c) and (d) Photographs of specular and diffuse reflection using laser light.
Fig 35-5c, p.1098

70. Figure 35.5 (c) and (d) Photographs of specular and diffuse reflection using laser light.
Fig 35-5d, p.1098

71. Active Figure 35. 6 According to the law of reflection, I = i
Active Figure 35.6 According to the law of reflection, I = i. The incident ray, the reflected ray, and the normal all lie in the same plane.
Fig 35-6, p.1099

72. Figure 35.7 (Example 35.2) (a) Mirrors M1 and M2 make an angle of 120° with each other. (b) The geometry for an arbitrary mirror angle.
Fig 35-7, p.1100

73. Figure 35.7 (Example 35.2) (a) Mirrors M1 and M2 make an angle of 120° with each other.
Fig 35-7a, p.1100

74. Figure 35. 8 Applications of retroreflection
Figure 35.8 Applications of retroreflection. (a) This panel on the Moon reflects a laser beam directly back to its source on the Earth.
Fig 35-8a, p.1101

75. Figure 35. 8 Applications of retroreflection
Figure 35.8 Applications of retroreflection. (b) An automobile taillight has small retroreflectors that ensure that headlight beams are reflected back toward the car that sent them.
Fig 35-8b, p.1101

76. Figure 35. 8 Applications of retroreflection
Figure 35.8 Applications of retroreflection. (c) A light ray hitting a transparent sphere at the proper position is retroreflected.
Fig 35-8c, p.1101

77. Figure 35. 8 Applications of retroreflection
Figure 35.8 Applications of retroreflection. (d) This stop sign appears to glow in headlight beams because its surface is covered with a layer of many tiny retroreflecting spheres. What would you see if the sign had a mirror-like surface?
Fig 35-8d, p.1101

78. Figure 35.9 (a) An array of mirrors on the surface of a digital micromirror device. Each mirror has an area of about 16  m2.
Fig 35-9a, p.1101

79. Figure 35. 9 (b) A close-up view of two single micromirrors
Figure 35.9 (b) A close-up view of two single micromirrors. The mirror on the left is “on” and the one on the right is “off.”
Fig 35-9b, p.1101

80. Active Figure (a) A ray obliquely incident on an air–glass interface. The refracted ray is bent toward the normal because v2 < v1. All rays and the normal lie in the same plane.
Fig 35-10a, p.1102

81. Active Figure (b) Light incident on the Lucite block bends both when it enters the block and when it leaves the block.
Fig 35-10b, p.1102

82. Active Figure (a) When the light beam moves from air into glass, the light slows down on entering the glass and its path is bent toward the normal.
Fig 35-11a, p.1103

83. Active Figure (b) When the beam moves from glass into air, the light speeds up on entering the air and its path is bent away from the normal.
Fig 35-11b, p.1103

84. Figure 35. 12 Light passing from one atom to another in a medium
Figure Light passing from one atom to another in a medium. The dots are electrons, and the vertical arrows represent their oscillations.
Fig 35-12, p.1103

85. Figure 35.15 (Example 35.4) Refraction of light by glass.
Fig 35-15, p.1105

86. Figure (Example 35.6) (a) When light passes through a flat slab of material, the emerging beam is parallel to the incident beam, and therefore  1 =  3. The dashed line drawn parallel to the red ray coming out the bottom of the slab represents the path the light would take if the slab were not there. (b) A magnification of the area of the light path inside the slab.
Fig 35-16, p.1107

87. Figure (Example 35.6) (a) When light passes through a flat slab of material, the emerging beam is parallel to the incident beam, and therefore  1 =  3. The dashed line drawn parallel to the red ray coming out the bottom of the slab represents the path the light would take if the slab were not there.
Fig 35-16a, p.1107

88. Figure 35.16 (Example 35.6) (b) A magnification of the area of the light path inside the slab.
Fig 35-16b, p.1107

89. Fig 35-17, p.1108

90. Figure 35.17 Huygens’s construction for (a) a plane wave propagating to the right
Fig 35-17a, p.1108

91. Figure 35.17 Huygens’s construction for (b) a spherical wave propagating to the right.
Fig 35-17b, p.1108