Unit 13

163 Your Turn Solutions


1. A ray of light strikes a mirror at an angle of 53o with respect to the normal line drawn to the surface.

a. Sketch the incident ray as it strikes the mirror.

You should have a line that is 53o from a perpendicular line and 37o from the surface.

b. Determine the angle of reflection and sketch the reflected light ray.

The angle of reflection is also 53o from the normal line. Your sketch should have the same line, just reflected over the normal line you drew.

2. A ray of light incident upon a mirror makes an angle of 36o with respect to the mirror. Sketch the situation and determine the angle between the incident ray and the reflected ray.

Same idea for the sketch. Angle = 108o

3. A light ray is incident upon the set of mirrors as shown below.

a. Sketch the reflected ray (determining and sketching the angles of incidence and reflection) for the light ray as it reflects off of each mirror.

Your first angles should be 15o with respect to the mirror, 75o with respect to the normal. Your second angles should be 75o with respect to the mirror, 15o with respect to the normal.

b. Describe the relationship between the incoming ray and the final reflecting ray for right angled mirrors.

The incoming ray and the final relfecting rays are parallel.

4. A light ray is incident upon the set of mirrors as shown below. Sketch the reflected ray (determining and sketching the angles of incidence and reflection) for the light ray as it reflects off of each mirror.

Your first angles should be 15o with the mirror, 75o with the normal.

Your second angles should be 30o with respect to the mirror, 60o with the normal.

Your third angles should be 60o with respect to the mirror, 30o with the normal.

5. In trial f there was a large object distance compared to the focal length. How did the image distance compare to the focal length? Explain.

The image distance would be slightly larger than the focal length. The inverse of the object distance will be subtracted off of the focal length since

A smaller number will always have a larger inverse. Therefore, whatever is subtracted off of the focal length will cause the image distance to get larger.

6. In trial h there was a large image distance compared to f. How did the object distance compare to f? Explain.

Since the last equation can be altered to

7. What does it mean when the magnification is negative?

Negative magnification means that the imageis inverted.

8. What does it mean when the focal length is negative?

The focal length is negative if the mirror is conve because the focal point is behind the mirror.

9. In trial j the object distance was equal to the focal length. What type of image did you get?

Imaginary.

10. An object is placed 30 cm from a concave mirror with a 10 cm focal length.

a. Determine the image location.

b. Describe the image. (Virtual or Real, Upright or Inverted, Larger or Smaller)

Smaller since 15 cm is less than 30 cm.

c. Determine the magnification of the bulb.

d. Determine the height of the image.

??????????????? NO ORIGINAL HEIGHT ???????????????

11. Determine the distance from the mirror to the image for an object that is 15 cm from a concave mirror that has a focal length of 10 cm.

12. How far away from the mirror and how tall is the image formed for a 3 cm tall object that is 10 cm from a concave mirror with a focal length of 6 cm.

13. A real image is 12 cm from a concave mirror which has a 4 cm focal length. Determine the object distance.

14. The focal length of a convex mirror is 20 cm. A newspaper is 6 cm from the mirror.

a. Determine the image location.

b. Describe the image. (Virtual or Real, Upright or Inverted, Larger or Smaller)

The image is virtual, upright, larger.

c. Determine the magnification of the bulb.

d. Determine the height of the image.

??????????? NO ORIGINAL HEIGHT ???????????

15. A concave mirror has a focal length of 15 cm and a 28 cm tall object placed 32 cm in front of the mirror.

a. Determine the distance from the mirror to the image.

b. Is the image real or virtual? Explain.

The image is real because it has a positive image distance.

c. Is the image upright or inverted? Explain.

The image is inverted since it is real.

d. Determine the magnification of the object.

16. A man is shaving in a concave mirror which provides him with an upright image of his chin, magnified 3 times when he is 12 cm away from the mirror. Determine the focal length of the mirror.


Glenbrook South Physics Team - Tom Henderson, John Lewis, Neil Schmidgall, Dave Smith, Suzanne Webb & Brian Wegley
4000 West Lake Ave
Glenview, IL 60025 - 1200
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Page Maintained by: Brian Wegley

Last Updated: October 8, 1997