The light waves represented by the three rays shown in the diagram all have the same frequency. 4.7 wavelengths fit into layer 1, 3.2 wavelengths fit into layer 2, and 5.3 wavelengths fit into layer 3. Rank the layers according to their indices of refraction, least to greatest.

A.1, 2, 3
B.2, 1, 3
C.3, 1, 2
D.3, 2, 1
E.1, 3, 2

2. Interference of light is evidence that:
A.the speed of light is very large
B.light is a transverse wave
C.light is electromagnetic in character
D.light is a wave phenomenon
E.light does not obey conservation of energy

3. In a Young's double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of:
A.a fourth of a wavelength
B.a half a wavelength
C.a wavelength
D.three-fourths of a wavelength
E.none of the above

4. Waves from two slits are in phase at the slits and travel to a distant screen to produce the second minimum of the interference pattern. The difference in the distance traveled by the wave is:
A.half a wavelength
B.a wavelength
C.three halves of a wavelength
D.two wavelengths
E.five halves of a wavelength

5. A monochromatic light source illuminates a double slit and the resulting interference pattern is observed on a distant screen. Let d = center-to-center slit spacing, a = individual slit width, D = screen-to-slit distance, E = adjacent dark line spacing in the interference pattern. The wavelength of the light is then:
A.dE /D
D.E D/a

6. Light from a small region of an ordinary incandescent bulb is passed through a yellow filter and then serves as the source for a Young's double-slit experiment. Which of the following changes would cause the interference pattern to be more closely spaced?
A.Use slits that are closer together
B.Use a light source of lower intensity
C.Use a light source of higher intensity
D.Use a blue filter instead of a yellow filter
E.Move the light source further away from the slits

7. In a Young's double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to:

8. Monochromatic light, at normal incidence, strikes a thin film in air. If l denotes the wavelength in the film, what is the thinnest film in which the reflected light will be a maximum?
A.much less than l


A lens with a refractive index of 1.5 is coated with a material of refractive index 1.2 in order to minimize reflection. If l denotes the wavelength of the incident light in air, what is the thinnest possible such coating?


10. A glass (n = 1.6) lens is coated with a thin film (n = 1.3) to reduce reflection of certain incident light. If l is the wavelength of the light in the film, the least film thickness is:
A.less than l/4
E.more than l

11. A soap film, 4 × 10–5 cm thick, is illuminated by white light normal to its surface. The index of refraction of the film is 1.50. Which wavelengths will be intensified in the reflected beam?
A.400 nm and 600 nm
B.480 nm and 800 nm
C.360 nm and 533 nm
D.400 nm and 800 nm
E.510 nm and 720 nm

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