Exam 4 Giancoli Chapters 23, 24, and 25 Instructor: Douglas Vardakas Name (4 points): Class: Physics 122 Semester: Spring 2020 Date: May 11, 2020 Part 1 Multiple Choice – Circle Best Answer (2 points each) Show work even for multiple choice questions 1. A ray of light in air is incident on a glass surface at an angle of 45 degrees. If the ray is refracted at an angle of 35 degrees as it passes into the glass, what is the index of refraction of the glass? a. 1.23 b. 1.41 c. 1.74 d. 2.13 2. What is the speed of light through a piece of clear plastic if its index of refraction is 1.7? a. 5.10x106 m/s b. 1.76x108 m/s c. 3.00x108 m/s d. 5.10x108 m/s 3. Which person provided the first definitive proof of the wave nature of light with the double slit experiment? a. Newton b. Young c. Planck d. Einstein 4. A light ray in plastic (n=1.45) hits an air/plastic boundary as shown below. The ray will be...? a. refracted into the air at 29.2º b. refracted into the air at 43.6º c. reflected back into the plastic at 29.2º d. reflected back into the plastic at 45.0º 5. Which of the following best describes the image formed by a converging lens when an object is placed between the focal point and the lens? a. inverted, real, magnified b. inverted, virtual, reduced c. upright, virtual, magnified d. upright, real, reduced 6. A concave mirror with a radius of curvature of 40 cm forms an image 15 cm behind the mirror. Where in front of the mirror was the object placed? a. 6.0 cm b. 8.6 cm c. 30 cm d. 60 cm 7. The image of an object placed in front of a convex mirror will... a. always be virtual b. always be larger than the object c. always be real d. always be in front of the mirror 8. The image of a distant object created by a concave mirror will be... a. formed at the focal point of the mirror b. formed at the mirror's center of curvature c. virtual, upright, and reduced d. real, upright, and magnified 9. Which surface would produce the most specular reflection? a. A snow covered field b. A concrete road c. A black chalkboard d. A mirror 10. The opposite of a specular reflection is… a. Refraction b. Interference c. Diffuse d. Diffraction 11. Which one of the following is not produced by refraction? a. An inferior mirage b. Twinkling stars c. Lingering sunset d. The image of your face in a mirror 12. Fiber optics is an application of... a. Interference b. Dispersion c. Refraction d. Total internal reflection 13. A rainbow (the spectrum of color produced by water droplets in the air) is an example of... a. Dispersion b. Diffraction c. Interference d. Scattering Page 2 14. The spectrum of color seen reflected off of a CD is caused by... a. Dispersion b. Polarization c. Interference d. Scattering 15. When white light is sent through the combination of a yellow filter and a blue filter, what color emerges? a. Blue b. Red c. Green d. no color 16. When cyan light and yellow light are combined together on a screen, what color is created? a. White b. Green c. Magenta d. Light green 17. What color light will produce white light when mixed with magenta light? a. Cyan b. Blue c. Green d. Red 18. Which one of the following effects is not produced by interference? a. Newton's rings b. The spectrum of color seen using a prism c. Iridescent feathers d. The spectrum of color seen on a soap bubble 19. Two lenses are used to construct a compound lens. If one is a converging lens with a focal length of 10 cm and the other is a diverging lens with a focal length of 5 cm, find the focal length of the combination. a. -0.100 cm b. +0.300 cm c. +3.33 cm d. -10.0 cm 20. A person's near point is 55 cm. What is the minimum power lens that would enable the person to see newsprint at 25 cm? a. +0.022 diopters b. +2.18 diopters c. +4.58 diopters d. +5.82 diopters Page 3 Part 2 Answer the following questions, showing ALL your work. Box your final answer and include units. Each question is worth 9 points. 21. For the following mirror, locate the image by drawing a ray diagram (3 rays) and describe the image as (inverted or upright, real or virtual, magnified or reduced). a. Upright, virtual, reduced b. Inverted, real, magnified c. Inverted, virtual, magnified d. Upright, real, reduced 22. For the following lens, locate the image by drawing a ray diagram (3 rays) and describe the image as (inverted or upright, real or virtual, magnified or reduced). a. Upright, virtual, reduced b. Inverted, real, magnified c. Inverted, virtual, magnified d. Upright, real, reduced Page 4 Part 3 Answer the following questions, showing ALL your work. Box your final answer and include units. Each question is worth 14 points. 23. A compound optical system consists of two converging lenses as shown below. Locate and describe (real or virtual) the final image of an object placed 7 cm in front of the first lens. No ray diagram is required. (7 points) a. Upright, virtual b. Inverted, virtual c. Upright, real d. Inverted, real 24. Determine the net magnification of the image. (7 points) a. 0.33 b. 5.25 c. 6.67 d. 7.5 Page 5 25. To give a glass window a red hue, a thin polymer (n = 1.6) coating is applied to the glass (n = 1.4). What is the minimum thickness of the coating required to produce this effect? Take the wavelength of red light to be 650 nm and answer with 3 significant digits. a. 102 nm b. 203 nm c. 163 nm d. 321 nm 26. A double slit aperture is illuminated with HeNe laser light (λ = 638 nm). The pattern observed on a screen placed 2.5 m from the aperture is shown below. If the distance between the 2 nd order minima on either side of the central bright spot is 25 cm, determine the spacing between the slits. Hint: carefully determine m for 2nd order minima. a. 38.3 μm b. 9.6 μm c. 25.5 μm d. 19.1 μm Page 6
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