Chapter 18: Questions

1. With your eye positioned relative to a plane mirror as shown in the figure, which of the circles will you see, a, b, or c?

Figure 18.K Which circle will you see?

2. Why do some ambulance companies write on the front of their vehicles "backward"? Why would they not write it that way on the side or back of the vehicle?

Figure 18.L Cartoon with sign painter holding work order and saying "I did just what it says here-paint 'AMBULANCE backward'."

3. What is the minimum length of a mirror you need to see your entire height-from the top of your head to the bottom of your toes? Does it make any difference how far you are from the mirror? Diagrams will help.
4. How many images are produced in the corner where two plane mirrors come together perpendicular to each other?
5. How many images are produced in a 3D corner where three plane mirrors come together, mutually perpendicular to each other?
6. How many images will be produced by two plane mirrors that are placed together at 45?

Figure 18.M Two mirrors are at 45 to each other.

7. Use a diagram to show that if a beam of light is reflected from a mirror and the mirror is moved through some angle, the reflected beam will be moved through twice that angle. This employed in an "optical lever" arrangement that is sometimes used in physics experiments to measure very small angular displacements.
8. Where, compared to the focal point, should an object be placed, in front of a concave mirror, to produce a real image? Where should it be placed to produce a virtual image?
9. Carefully draw a ray diagram for an object placed 50 cm from a concave mirror that has a focal length of 15 cm. Describe the image that is formed.
10. Construct a ray diagram (always to scale!) to locate and characterize the image produced by a concave mirror whose focal length is 20 cm when an object is placed 30 cm away. Is the image real or virtual? Is it right side up or inverted? Is it enlarged or reduced?
11. Use a carefully drawn ray diagram to describe the image produced by a concave mirror with focal length of f = 20 cm when an object is 15 cm away from the mirror.
12. Carefully draw a ray diagram to locate and describe the image produced by a concave mirror whose focal length is 10 cm when an object is placed 30 cm away. Is the image real or virtual? Is it right side up or upside down? Is it larger or smaller than the object?
13. Carefully draw a ray diagram to locate and characterize the image produced by a convex mirror that has a focal length of - 15 cm when an object is located 30 cm away from the mirror. What is the magnification?
14. Use a carefully drawn ray diagram to locate and describe the image produced by a convex mirror with a focal length of f = - 20 cm for an object located 10 cm away from the mirror. Is the image real or virtual? Is it right side up or inverted? Is it larger or smaller than the object? What is the magnification?
15. As described in the Home Demos, you can adjust the position of a candle in front of a concave mirror until you see the candle burning at both ends. Construct a ray diagram for this situation.
16. What are some of the benefits and drawbacks to using a concave mirror as a rearview mirror on a car?

Figure 18.N No caption

17. Why might a store place a convex mirror someplace where it can be seen by a check-out clerk?

Figure 18.O No caption

18. A scuba diver, under a very smooth body of water, looks up and sees an overhanging limb of a tree that appears to be one meter above the smooth surface of the water. Does an observer in the air see the tree limb closer to the water or farther away from the water? Explain your answer, of course.
19. Where, in relation to the focal point, should an object be placed, in front of a converging lens, to produce a real image? Where should it be placed to produce a virtual image?
20. Carefully draw a ray diagram for an object placed 50 cm from a converging lens that has a focal length of 15 cm. Describe the image that is formed. Is the image real or virtual? Is it right side up or inverted? Is it enlarged or reduced?
22. Construct a ray diagram to locate and characterize the image produced by a converging lens whose focal length is 50 cm for an object placed 75 cm away. What is the magnification?
23. Use a carefully drawn ray diagram to describe the image produced by a converging lens that has a focal length of f = 30 cm with an object 15 cm away from the lens. What is the magnification?
24. Carefully draw a ray diagram to locate and describe the image produced by a converging lens whose focal length is 15 cm when an object is placed 45 cm away.
25. Carefully draw a ray diagram to locate and characterize the image produced by a diverging lens with a focal length of - 20 cm when an object is located 40 cm away from the lens. Is the image real or virtual? Is it right side up or upside down? Is it larger or smaller than the object?
26. Carefully draw a ray diagram to locate and describe the image produced by a diverging lens with a focal length of - 30 cm when an object is located 15 cm away from the lens. Is the image real or virtual? Is it right side up or inverted? Is it larger or smaller than the object?