Chapter 25 (pHYSICAL/wAVE OPTICS)
1. Interference effects observed in the early 1800’s were instrumental in supporting a concept of the existence of which property of light?
a. polarization
b. particle nature
c. wave nature
d. electro‑magnetic character
2. If a wave from one slit of a Young’s double slit set‑up arrives at a point on the screen one wavelength behind the wave from the other slit, what is observed at that point?
a. dark fringe
b. bright fringe
c. multi‑colored fringe
d. gray fringe, neither dark nor bright
3. The blue tint of a coated camera lens is largely caused by what effects?
a. diffraction
b. refraction
c. polarization
d. interference
4. A Young’s double slit has a slit separation of 2.5 ´ 10‑5 m on which a monochromatic light beam is directed. The resultant bright fringes on a screen 1.0 m from the double slit are separated by 2.3 ´ 10‑2 m. What is the wavelength of this beam? (1 nm = l0‑9 m)
a. 373 nm
b. 454 nm
c. 575 nm
d. 667 nm
5. Two narrow slits are 0.025 mm apart. When a laser shines on them, bright fringes form on a screen that is a meter away. These fringes are 3.0 cm apart. What is the separation between the second order bright fringe and the central fringe?
a. 8.6 cm
b. 6.0 cm
c. 5.3 cm
d. 2.6 cm
6. What is the minimum thickness of a soap bubble film (n = 1.46) on which light of wave length 500 nm shines, assuming one observes constructive interference of the reflected light?
a. 63 nm
b. 86 nm
c. 125 nm
d. 172 nm
7. Light of wavelength 500 nm shines on a soap bubble film (n = 1.46). For what soap film thickness, other than the minimum thickness, will constructive interference occur?
a. 63 nm
b. 86 nm
c. 172 nm
d. 257 nm
8. A silicon monoxide thin film (n = 1.45) of thickness 97.4 nm is applied to a camera lens made of glass (n = 1.58). This will result in a destructive interference for reflected light of what wavelength?
a. 720 nm
b. 616 nm
c. 565 nm
d. 493 nm
9. A beam of unpolarized light in air strikes a flat piece of glass at an angle of incidence of 54.2˚. If the reflected beam is completely polarized, what is the index of refraction of the glass?
a. 1.60
b. 1.39
c. 1.52
d. 2.48
10. In order to produce a sustained interference pattern by light waves from multiple sources, which of the following conditions must be met?
a. sources are coherent
b. sources are monochromatic
c. both choices above are valid
d. none of the choices above are valid
11. In a Young’s double slit interference apparatus, by what factor is the distance between adjacent light and dark fringes changed when the separation between slits is tripled?
a. 1/9
b. 1/3
c. 1.0
d. 3.0
12. In a Young’s double slit interference apparatus, the separation between slits and screen is tripled. The distance between adjacent light and dark fringes changes by a factor of:
a. 1/9
b. 1/3
c. 1.0
d. 3.0
13. In a Young’s double slit interference apparatus, by what factor is the distance between adjacent light and dark fringes changed when the wavelength of the source is tripled?
a. 1/9
b. 1/3
c. 1.0
d. 3.0
14. A Fraunhofer diffraction pattern is created by monochromatic light shining through which of the following?
a. single slit
b. double slit
c. triple slit
d. more than 3 slits
15. The dark spot observed in the center of a Newton’s rings pattern is attributed to which of the following?
a. polarization of light when reflected
b. polarization of light when refracted
c. phase shift of light when reflected
d. phase shift of light when refracted
16. A Young’s double slit apparatus is set up so that a screen is positioned 1.6 m from the double slits and the spacing between the two slits of 0.04 mm. What is the distance between alternating bright fringes on the screen if the light source has a wavelength of 630 nm? (1 nm = 10‑9 m)
a. 0.016 m
b. 0.025 m
c. 0.032 m
d. 0.047 m
17. A Young’s double-slit apparatus is set up. A screen is positioned 1.6 m from the double slits and the spacing between the two slits is 0.04 mm. The distance between alternating bright fringes is 1.42 cm. Find the light source wavelength? (1 nm = 10‑9 m)
a. 430 nm
b. 490 nm
c. 280 nm
d. 355 nm
18. A Young’s double slit apparatus is set up where a screen is positioned 0.8 m from the double slits. If the distance between alternating bright fringes is 0.95 cm and the light source has a wave length of 580 nm, what is the separation of the double slits?
a. 2.8 ´ 10‑5 m
b. 4.9 ´ 10‑5 m
c. 5.6 ´ 10‑5 m
d. 6.0 ´ 10‑5 m
19. A Young’s double-slit apparatus is set up. The source wavelength is 430 nm and the double-slit spacing is 0.04 mm. At what distance from the double slits should the screen be placed if the spacing between alternating bright fringes is to be 2.4 cm?
a. 1.6 m
b. 2.23 m
c. 2.4 m
d. 2.9 m
20. A light source simultaneously emits light of two wavelengths, 480 nm and 560 nm, respectively. The source is used in a double‑slit interference experiment where the slit spacing is a 0.04 mm and the distance between double slits and the screen is 1.2 m. What is the separation between the second‑order bright fringes of the two wavelengths as they appear on the screen? (1 nm = 10‑9 m)
a. 0.16 cm
b. 0.32 cm
c. 0.48 cm
d. 0.64 cm
21. What wavelength monochromatic source in the visible region (390 to 710 nm) can be used to constructively reflect off a soap film (n = 1.46) if the film is 77 nm thick?
a. 409 nm
b. 430 nm
c. 450 nm
d. 558 nm
22. What wavelength monochromatic source in the visible region (390 to 710 nm) can be used to constructively reflect off a soap film (n = 1.46) if the film is 240 nm thick?
a. 467 nm
b. 562 nm
c. 587 nm
d. 480 nm
23. A silicon monoxide (n = 1.45) film of 100 nm thickness is used to coat a glass camera lens (n = 1.56). What wavelength of light in the visible region (390 to 710 nm) will be most efficiently transmitted by this system? (1 nm = 10‑9 m)
a. 400 nm
b. 492 nm
c. 624 nm
d. 580 nm
24. A silicon monoxide (n = 1.45) film of 270 nm thickness is used to coat a glass camera lens (n = 1.56). What wavelength of light in the visible region (390 to 710 nm) will be most efficiently transmitted by this system? (1 nm = 10‑9 m)
a. 409 nm
b. 492 nm
c. 522 nm
d. 638 nm
25. Light of wavelength 610 nm is incident on a slit of width .20 mm and in interference pattern is produced on a screen that is 1.5 m from the slit. What is the width of the central bright fringe? (1 nm = 10‑9 m)
a. 0.68 cm
b. 0.92 cm
c. 1.22 cm
d. 1.35 cm
26. Light of wavelength 610 nm is incident on a slit of width .20 mm and in interference pattern is produced on a screen that is 1.5 m from the slit. What is the distance of the second dark fringe as measured from the center of the bright fringe? (1 nm = l0‑9 m)
a. 0.68 cm
b. 0.92 cm
c. 1.22 cm
d. 1.35 cm
27. Polarization of light can be achieved using a dichroic material like Polaroid by which of the following processes?
a. reflection
b. double refraction
c. selective absorption
d. scattering
28. Polarization of light can be achieved using birefringent materials by which of the following processes?
a. reflection
b. double refraction
c. selective absorption
d. scattering
29. When the sun is located near one of the horizons, an observer looking at the sky directly overhead will view partially polarized light. This effect is due to which of the following processes?
a. reflection
b. double refraction
c. selective absorption
d. scattering
30. An unpolarized beam of light is incident on a pane of glass (n = 1.56) such that the reflected component coming off the glass is completely polarized. What is the angle of incidence in this case?
a. 32.7˚
b. 41.0˚
c. 49.0˚
d. 57.3˚
31. A beam of light of 650 nm wavelength is incident along the normal to two closely spaced parallel glass plates. For what air gap separation between the plates will the transmitted beam be of maximum intensity? (1 nm = 10‑9 m)
a. 81 nm
b. 163 nm
c. 325 nm
d. 488 nm
32. Two closely spaced parallel glass plates are separated by 750 nm. What wavelength light source in the visible region (390 nm ‑ 710 nm) will experience maximum transmission through the two plates?
a. 500 nm
b. 429 nm
c. 600 nm
d. 684 nm
33. Two flat glass plates are in contact along one end and are separated by a sheet of paper 4.0 ´ 10‑6 m thick at the other end. The top plate is illuminated by a monochromatic light source of 490 nm wavelength. How many dark parallel bands will be evident across the top plate? (1 nm = 10‑9 m)
a. 7
b. 9
c. 13
d. 17
34. Two flat glass plates are in contact along one end and are separated by a sheet of tissue paper at the other end. A monochromatic source of 490 nm illuminates the top plate. If 21 dark bands are counted across the top plate, what is the paper thickness?
a. 2.7 ´ 10-6 m
b. 3.4 ´ 10-6 m
c. 4.9 ´ 10-6 m
d. 5.8 ´ 10-6 m
35. At what angle is the sun above the horizon if its light is found to be completely polarized when it is reflected from the top surface of a slab of glass (n = 1.65)?
a. 31.2˚
b. 44.4˚
c. 58.8˚
d. 66.6˚
36. A Fraunhofer diffraction pattern is produced from a light source of 580 nm. The light goes through a single slit and onto a screen a meter away. The first dark fringe is 5.0 mm from the central bright fringe. What is the slit width? (1 nm = 10‑9 m)
a. 0.24 mm
b. 0.12 mm
c. 0.10 mm
d. 0.81 ´ 10‑5 m
37. Waves from a radio station with a wavelength of 400 m arrive at a home receiver a distance 30 km away from the transmitter by two paths. One is a direct‑line path and the second by reflection from a mountain directly behind the receiver. What is the minimum distance between the mountain and receiver such that destructive interference occurs at the location of the listener?
a. 100 m
b. 200 m
c. 300 m
d. 400 m
38. Two beams of coherent light are shining on the same piece of white paper. With respect to the crests and troughs of such waves, darkness will occur on the paper where:
a. the crest from one wave overlaps with the crest from the other.
b. the crest from one wave overlaps with the trough from the other.
c. the troughs from both waves overlap.
d. darkness cannot occur as the two waves are coherent.
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39. After light from a source passes through two slits, a first order bright spot is seen on the wall at point P. Which distance is equal to the wavelength of the light?
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a. the extra distance one beam must travel
b. the distance between beams as they leave the slit
c. the distance of point P from the central point of the interference pattern
d. the distance between slits
40. If the 2nd order fringe in Young’s double slit experiment occurs at an angle of 45˚, what is the relationship between the wavelength l and the distance between slits, d.
a. d = 1.414l
b. d = 2l
c. d = 2.83l
d. d = 4l
41. When light shines on a lens placed on a flat piece of glass, interference occurs, which causes circular fringes called Newton’s rings. The two beams that are interfering come:
a. from the top and bottom surface of the lens.
b. from the top surface of the lens and the top surface of the piece of glass.
c. from the bottom surface of the lens and the top surface of the piece of glass.
d. from the top and bottom surface of the flat piece of glass.
42. The center spot of Newton’s rings is dark. This destructive interference occurs because
a. the two beams travel distances that are different by half a wavelength.
b. both waves change phase by 180˚ as they are reflected.
c. one beam changes phase by 180˚ when it is reflected.
d. both waves have a trough.
43. When light passes from a material with a high index of refraction into material with a low index of refraction:
a. none of the light is reflected.
b. some light is reflected without a change of phase.
c. some light is reflected with a 180˚ change of phase.
d. the light that is not reflected has a 108 ˚ change of phase.
44. Light is reflecting off a wedge‑shaped thin piece of glass producing bright and dark interference fringes. If a certain location has a bright fringe, a nearby point will have a dark fringe if the thickness of the glass increases by:
a. 1/8 of a wavelength of the light.
b. 1/4 of a wavelength of the light.
c. 1/2 of a wavelength of the light.
d. one wavelength of the light.
45. Which statement is correct?
a. A double slit interference pattern does not require diffraction.
b. A single slit diffraction pattern does not require interference.
c. Diffraction, refraction, and reflection all can cause the path of light not to be a straight line path.
d. Polarization involves interference.
46. Polaroid sunglasses help when skiing on snow on a sunny day by reducing the sunlight from the snow. This light from the snow has been polarized by:
a. selective absorption.
b. reflection.
c. double refraction.
d. scattering.
47. Polaroid material made from a dichroic substance polarizes light by:
a. selective absorption.
b. reflection.
c. double refraction.
d. scattering.
48. When light from a single point passes through calcite it often forms two images, each of which is formed from light that has been polarized by:
a. selective absorption.
b. reflection.
c. double refraction.
d. scattering.
49. The blue light from the sky has been polarized by:
a. selective absorption.
b. reflection.
c. double refraction.
d. scattering.
50. A Young’s interference experiment is conducted with blue‑green argon laser light (l = 515 nm). The separation between the slits is 0.5 mm and the interference pattern appears on a screen 3.3 m away. What is the spacing between the bright fringes?
a. 1.7 mm
b. 3.4 mm
c. 5.1 mm
d. 6.8 mm
51. Helium‑neon laser light (l = 632.8 nm) is sent through a 0.3 mm‑wide single slit. What is the width of the central maximum on a screen 1 m in back of the slit?
a. 2.02 mm
b. 3.13 mm
c. 4.22 mm
d. 5.31 mm
52. A soap bubble (n = 1.35) is floating in air. If the thickness of the bubble wall is 300 nm, which of the following wavelengths of visible light is strongly reflected?
a. 620 nm (red)
b. 580 nm (yellow)
c. 540 nm (green)
d. 500 nm (blue)
53. A puddle of water (n = 1.33) is covered with a very thin layer of oil (n = 1.20). How thick is the oil in the region that reflects light with a wavelength of 550 nm?
a. 207 nm
b. 229 nm
c. 458 nm
d. 550 nm
54.A possible means for making an airplane radar‑invisible is to coat the plane with an antireflective polymer. If radar waves have a wavelength of 3 cm and the index of refraction of the polymer is n = 1.5, how thick would the coating be?
a. 1 mm
b. 2 mm
c. 5 mm
d. 2 cm
55. A hair is placed at one edge between two flat glass plates. When this arrangement is illuminated with yellow light of wavelength (l = 600 nm), a total of 121 dark bands are counted starting at the point of contact between the plates. How thick is the hair?
a. 3.6 ´ 10‑5 m
b. 1.8 ´ 10‑5 m
c. 3.6 ´ 10-4 m
d. 1.8 ´ 10‑4 m
56. A thin film of magnesium fluoride (n = 1.38) is used to coat a camera lens (n = 1.56). Which of the following thicknesses of coating will not allow any strong reflections in the visible spectrum (l = 390 nm to l = 700 nm)?
a. 1 ´ 10‑5 cm
b. 2 ´ 10‑5 cm
c. 5 ´ 10‑5 cm
d. 1 ´ 10‑4 cm
57. How far above the horizon is the moon when its image reflected in calm water is completely polarized? (nwater = 1.333)
a. 7.7˚
b. 16.6˚
c. 22.2˚
d. 36.87˚
58. Sunlight reflected from a smooth ice surface is completely polarized. Determine the angle of incidence. (nice = 1.309)
a. 25.60˚
b. 47.89˚
c. 52.62˚
d. 56.26˚
59. If the polarizing angle for diamond is 67.5˚, what is the index of refraction of this material?
a. 2.00
b. 2.20
c. 2.42
d. 2.65
60. The critical angle for sapphire surrounded by air is 34.4˚. Calculate the polarizing angle for sapphire.
a. 60.5˚
b. 59.7˚
c. 58.6˚
d. 56.3˚
Chapter 25 - Answers
# Ans Difficulty # Ans Difficulty
1. C 1 31. C 2
2. B 1 32. A 2
3. D 1 33. D 3
4. C 2 34. C 3
5. B 2 35. A 2
6. B 2 36. B 2
7. D 2 37. B 2
8. C 2 38. B 1
9. B 2 39. A 1
10. C 1 40. C 2
11. B 1 41. C 1
12. D 1 42. C 1
13. D 1 43. B 1
14. A 1 44. B 1
15. C 1 45. C 1
16. B 2 46. B 1
17. D 2 47. A 1
18. B 2 48. C 1
19. B 2 49. D 1
20. C 2 50. B 2
21. C 2 51. C 2
22. A 2 52. C 2
23. D 2 53. B 3
24. C 2 54. C 2
25. B 2 55. A 3
26. B 2 56. A 3
27. C 1 57. D 2
28. B 1 58. C 2
29. D 1 59. C 2
30. D 2 60. A 3