Physics 126 Practice Exam #1 Chapters 25, 26, 27 Professor Siegel

Transcription

1 Physics 126 Practice Exam #1 Chapters 25, 26, 27 Professor Siegel Name: Lab Day: 1. Which one of the following phrases most accurately describes the term wave front? A) the surface of a plane mirror B) the surface of a convex mirror C) a surface upon which a wave is incident D) a surface of constant phase within a wave E) a surface that is parallel to the direction of wave propagation 2. Which one of the following statements concerning rays is false? A) Rays point in the direction of the wave velocity. B) Rays point outward from the wave source. C) Rays are parallel to the wave front. D) Rays are radial lines that originate from a point source of waves. E) Rays for a plane wave are parallel to each other. Page 1

2 3. A ray of light is reflected from two plane mirror surfaces as shown in the figure. What are the correct values of α and β? A) B) C) D) E) Value of α Value of β The radius of curvature of a spherical convex mirror is 52 cm. What is its focal length? A) +26 cm B) 26 cm C) +52 cm D) 52 cm E) +104 cm 5. A concave mirror in an amusement park has a radius of curvature of 4.0 m. A child stands in front of the mirror so that she appears 3.0 times taller than her actual height. If the image is upright, how far is she standing from the mirror? A) 1.1 m B) 1.3 m C) 2.8 m D) 3.0 m E) 4.5 m Page 2

3 6. A woman stands 2.0 m in front of a convex mirror and notices that her image height is 1/4 of her actual height. Determine the radius of curvature of the mirror. A) 0.67 m B) 1.3 m C) 2.0 m D) 4.0 m E) 6.0 m 7. An object is placed 20 cm in front of a concave spherical mirror that has a radius of curvature 60 cm. Which one of the following phrases best describes the image? A) virtual and located at infinity B) real and located 60 cm from the mirror C) real and located 120 cm from the mirror D) virtual and located 60 cm from the mirror E) virtual and located 120 cm from the mirror 8. A concave mirror is found to focus parallel rays at a distance of 18 cm. Where is the image formed when an object is placed 6.0 cm in front of the mirror? A) 11 cm in front of the mirror B) 18 cm behind the mirror C) 3.6 cm in front of the mirror D) 9.0 cm behind the mirror E) 9.0 cm in front of the mirror 9. A 6.0-ft tall football player stands in front of a plane mirror. How tall must the mirror be so that the football player can see his full-sized image? A) 2.0 ft B) 2.5 ft C) 3.0 ft D) 3.5 ft E) 6.0 ft Page 3

4 10. The table lists the index of refraction for various substances at 20 C for light with a wavelength of 589 nm in a vacuum. Through which substance will light with a vacuum wavelength of 589 nm travel with the greatest speed? A) fused quartz B) crown glass C) ethyl alcohol D) carbon tetrachloride E) crystalline quartz 11. What is the frequency of light that has a wavelength in water of 788 nm if the refractive index for this light is 1.33? A) Hz B) Hz C) Hz D) Hz E) Hz 12. A ray of light passes from air into a block of glass with a refractive index of 1.59 as shown in the figure. Note: The drawing is not to scale. What is the value of the distance D? A) 1.42 cm B) 1.66 cm C) 1.93 cm D) 2.19 cm E) 2.38 cm Page 4

5 13. Which one of the following expressions determines the critical angle for quartz (n = 1.5) immersed in oil (n = 1.1)? A) θc = 1.5/1.1 B) θc = sin 1 (1.1/1.5) C) θc = sin (1.1/1.5) D) θc = tan 1 (1.1/1.5) 14. What is the Brewster angle when light is reflected from a plastic plate (n = 1.575) submerged in ethyl alcohol (n = 1.362)? A) 68.3 B) 40.8 C) 59.8 D) 30.1 E) An object is placed 6.5 cm from a thin converging lens with a focal length of 14 cm. Which one of the following statements is true concerning the image? A) The image is virtual and 6.0 cm from the lens. B) The image is virtual and 12 cm from the lens. C) The image is real and 3.0 cm from the lens. D) The image is real and 6.0 cm from the lens. E) The image is real and 12 cm from the lens. 16. A converging lens is used to focus light from a small bulb onto a book. The lens has a focal length of 10.0 cm and is located 40.0 cm from the book. Determine the distance from the lens to the light bulb. A) 8.6 cm B) 13 cm C) 20 cm D) 30 cm E) 50 cm Page 5

6 17. A converging lens with a focal length of 12 cm produces a 3-cm high virtual image of a 1-cm high object. Which entry in the table below is correct? image distance location of image A) 8 cm same side of lens as object B) C) D) E) 8 cm opposite side of lens from object 12 cm opposite side of lens from object 24 cm opposite side of lens from object 24 cm same side of lens as object 18. Joseph uses a converging lens (f = 0.12 m) to read a map located m from the lens. What is the magnification of the lens? A) +3.4 B) +3.0 C) +1.7 D) E) Use the following to answer questions 19-20: A 4.0-cm object is placed 30.0 cm from a converging lens that has a focal length of 10.0 cm as shown in the diagram. Note: The diagram is not drawn to scale. Page 6

7 19. Where is the image located? A) 15 cm to the left of the lens B) 7.5 cm to the left of the lens C) 7.5 cm to the right of the lens D) 15 cm to the right of the lens E) 30 cm to the right of the lens 20. Determine the height and orientation of the image. A) 2 cm and upright B) 1 cm and inverted C) 2 cm and inverted D) 8 cm and upright E) 8 cm and inverted 21. Two identical light waves, A and B, are emitted from different sources and meet at a point P. The distance from the source of A to the point P is LA; and the source of B is a distance LB from P. Which one of the following statements is necessarily true concerning the interference of the two waves? A) A and B will interfere constructively because their amplitudes are the same. B) A and B will interfere constructively if LA = LB. C) A and B will interfere destructively if LA LB = mλ where m = 0, 1, 2, 3,... D) A and B will interfere destructively if LA is not equal to LB. E) A and B will interfere constructively because their wavelengths are the same. 22. What is the minimum (non-zero) thickness of a benzene (n = 1.501) thin film that will result in constructive interference when viewed at normal incidence and illuminated with orange light (λvacuum = 615 nm)? A glass slide (ng = 1.620) supports the thin film. A) 51.0 nm B) 306 nm C) 204 nm D) 102 nm E) 76.0 nm 23. Light of wavelength nm passes through a diffraction grating. The m = 0 and m = 1 bright spots are 6.0 cm apart on a screen positioned 2.0 m from the grating. What is the spacing between the slits in the grating? A) 23.3 μm B) 42.0 μm C) 46.7 μm D) 73.8 μm E) 124 μm Page 7

8 24. Which one of the following statements best explains why the diffraction of sound is more apparent than the diffraction of light under most circumstances? A) Sound requires a physical medium for propagation. B) Sound waves are longitudinal, and light waves are transverse. C) Light waves can be represented by rays while sound waves cannot. D) The speed of sound in air is six orders of magnitude smaller than that of light. E) The wavelength of light is considerably smaller than the wavelength of sound. 25. Light is incident on two slits that are separated by 0.2 mm. The figure shows the resulting interference pattern observed on a screen 1.0 m from the slits. Determine the wavelength of light used in this experiment. A) 0.05 nm B) 0.50 nm C) 50 nm D) 500 nm E) 5000 nm Page 8

9 Answer Key 1. D 2. C 3. B 4. B 5. B 6. B 7. D 8. D 9. C 10. C 11. D 12. D 13. B 14. E 15. B 16. B 17. E 18. B 19. D 20. C 21. B 22. C 23. A 24. E 25. D Page 9