Name: Class: Date: Exam 4 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Mirages are a result of which physical phenomena a. interference c. reflection b. refraction d. diffraction 2. Which of these is the appropriate name for this lens? a. convex-concave d. plano-convex b. bi-concave e. none of these c. convex 3. This figure shows a lens with an object to the left and 4 rays drawn from this object. The black dots represent the focal point of the lens. Which of the rays is not possible? a. a c. c b. b d. d 1
Name: 4. This figure shows a system of lenses with focal lengths f 1 and f 2. The object is 20 cm from the first lens. What is the position of the final image with respect to the second lens? a. 50 cm to the right of lens 2 c. 30 cm to the left of lens 2 b. 20 cm to the right of lens 2 d. 60 cm to the right of lens 2 5. A convex lens forms a real image of an object with a positive object distance. Which of these best describes the magnification? a. M is positive c. not enough information given b. M is negative 2
Name: 6. This figure shows what happens to light of different wavelengths when focused by a convex lens. What is this physical phenomena called? a. dispersion c. interference b. chromatic aberration d. spherical aberration 7. A converging lens has a focal length of 30 cm. If an object is at 20 cm, which of these describes the image: a. real and upright c. virtual and inverted b. virtual and upright d. real and inverted 8. A converging lens (convex) has a focal length of 10 cm. An object is at 20 cm. What is the magnification of the image? a. -1 c. 1 b. 0.5 d. -2 9. A diverging or concave lens has a focal length of ±20 cm (is either positive or negative). What is the image distance for an object at 10 cm? a. -7 cm c. -10 cm b. -20 cm d. 20 cm 10. Most cameras have an aperture to block the outer edges of the lens. What is the purpose of this aperture? a. to eliminate chromatic aberration c. to reduce the effects of spherical aberration b. to give the camera a smaller field of view d. to block flying monkeys from coming into your camera 3
Name: 11. This figure shows a light wave that is reflected off of a medium with index of refraction n 2. Based on the phase of the two waves, determine which of these statements is true: 12. a. n 1 =n 2 c. n 1 >n 2 b. Not enough information given d. n 1 <n 2 Light of wavelength 550 nm is incident upon a double slit apparatus. The two slits are separated by 5x10-6 m. What is the angular separation between the central maximum and the 2 rd order bright fringe? a. 13 c. 25 b. 16 d. Not enough information given 13. This figure shows an interference pattern created by a double slit apparatus. What difference in path lengths results in the maximum labeled by the arrow? a. 2λ c. 3λ b. 2.5 λ d. 3.5 λ 4
Name: 14. These 2 waves are: a. 90 out of phase c. in phase b. 180 out of phase d. 45 out of phase 15. Young s double slit experiment (in 1801) verified which of these a. light is ubiquitous c. light is a particle b. light is both a wave and particle d. light is a wave 16. The Fresnel spot is caused by a. diffraction through a diffraction grating c. diffraction through a single slit b. interference by a double slit d. diffraction around a circular disk 17. Two light sources emit waves of λ= 3 m which are in phase. The two waves from these sources meet at a distant point. Wave 1 traveled 6 m to reach the point, and wave 2 traveled 7 m. When the waves meet, they are a. out of phase, but not by 180 c. in phase b. out of phase by 180 18. A LASER beam (λ=632 nm) is incident on 2 slits 0.30 mm apart. How far is the first order bright fringe from the central maximum on a screen 5.0 meters from the double-slit apparatus? a. 0.011 meters c. 0.016 meters b. 2.4 meters d. 0.0021 meters 5
Name: 19. This figure shows two radio antennas, which are separated by 300 m. The antennas are emitting signals (identical in both wavelength and phase) simultaneously. A car is traveling north as shown in the figure. The car is at the second minimum of the interference pattern created by the two signals. What is the wavelength of the light? a. 45 m c. 632.8 nm b. 74 m d. 56 m 20. The diffraction pattern below arises from a single slit. If we would like to sharpen the pattern, i.e., make the central bright spot narrower, what should we do? a. decrease the slit width c. move the screen further away b. increase the wavelength of the light d. increase the slit width 6
Name: 21. A grating has 1x10-5 m between its slits and is illuminated with light of wavelength 500 nm. What is the highest order number that can be observed with the grating? a. 20 c. 5 b. 10 d. 15 22. A spectral line occurs at 12 in the first-order spectrum of a diffraction-grating spectrometer. If the grating s slits are separated by 2.0x10-6 m, what is the wavelength of the light? a. 630 nm c. 730 nm b. 420 nm d. 1100 nm 23. A single slit has a width of 1x10-4 m. Light of wavelength 500 nm is incident upon it and creates a interference pattern on a screen 2 meters away. What is the width of the central maximum on the screen? a. 0.01 m c. 0.02 m b. 0.05 m d. 0.005 m 24. Light of wavelength 1 mm is incident on a single slit of width 0.02 m. What is the angular separation between the central maximum and the 3rd order minimum? a. 7 c. 5 b. 10 d. 9 7
Name: 25. Red light of wavelength λ is incident on a single slit of width d, which forms a diffraction pattern on the screen. If you use violet light, which has wavelength λ/3, what must the slit width be in order to keep the diffraction pattern the same? a. 3d c. 2d b. 3d d. d/3 26. Which of these phenomena cause the interference pattern seen in thin films such as oil on water? a. refraction c. change in phase due to reflection b. the light s wavelength changes d. phased array in the oil 27. A diffraction grating has 4000 lines/cm. What is the slit separation? a. 2.5 µm b. 400 nm c. 4.0 µm d. 250 nm 28. The correct answer for this question is A. a. A c. C b. B d. D 8
Exam 4 Answer Section MULTIPLE CHOICE 1. ANS: B PTS: 1 2. ANS: A PTS: 1 3. ANS: D PTS: 1 4. ANS: D PTS: 1 5. ANS: B PTS: 1 6. ANS: B PTS: 1 7. ANS: B PTS: 1 8. ANS: A PTS: 1 9. ANS: A PTS: 1 10. ANS: C PTS: 1 11. ANS: D PTS: 1 12. ANS: A PTS: 1 13. ANS: A PTS: 1 14. ANS: B PTS: 1 15. ANS: D PTS: 1 16. ANS: D PTS: 1 17. ANS: A PTS: 1 18. ANS: A PTS: 1 19. ANS: B PTS: 1 20. ANS: D PTS: 1 21. ANS: A PTS: 1 22. ANS: B PTS: 1 23. ANS: C PTS: 1 24. ANS: D PTS: 1 25. ANS: D PTS: 1 26. ANS: C PTS: 1 27. ANS: A PTS: 1 DIF: 2 TOP: 24.8 The Diffraction Grating 28. ANS: A PTS: 1 1