1. Physics Light Review Problems
2009

2. #1
The tallest man in history was 2.72 m tall. The smallest woman in history had a height of 0.55 m. Suppose Robert is standing 5.0 m from a converging mirror that produces an image equal to Pauline’s height, what is the focal length of this mirror?
F = 0.84 m

3. #2
A human hair is about cm thick. If one places the hair 2.40 cm from a concave mirror with a focal length of 2.50 cm, how thick will the image of the hair appear?
Height of image = 0.2 cm

4. #3
A steel ball bearing with a radius of 1.5 cm forms an image of an object that has been placed 1.1 cm away from the bearing’s surface. Determine the image distance and magnification.
Q = cm; M = 0.41

5. #4
A spherical mirror is to be used in a motion-picture projector to from an inverted, real image 95 times as tall as the picture in a single frame of file. The image is projected onto a screen 13 m from the mirror. What type of mirror is required, and how far should it be from the film?
Concave; p = 0.14 m

6. #5
Consider a concave spherical mirror and an object. Is the image always inverted? Is the image always real? Give conditions for your answers.
No (only inverted when beyond f) No (only real when within f)

7. #6
The reflector of a radio telescope has a radius of curvature of m. How far above the reflector must the radio-detecting equipment be placed in order to obtain clear radio images?
132.5 m, which is the telescope’s focal length

8. #7
Describe the three rays used to predict image location in curved mirrors.
Parallel to PA, then through F
On a line containing F, then parallel to PA
Through C and back on C

9. #8
The real image of a tree is magnified times by a telescope’s primary mirror. If the tree’s image forms 35 cm in front of the mirror, what is the distance between the mirror and the tree?
P = 411 cm

10. #9
The real image of a tree is magnified times by a telescope’s primary mirror. If the tree’s image forms 35 cm in front of the mirror, what is the focal length of the mirror?
F = 32 cm

11. #10*
A child holds a candy bar 15.5 cm in front of the convex side-view mirror of an automobile. The image height is reduced by one-half. What is the radius of curvature of the mirror?
R = cm

12. #11 What could you do to determine if an image is real or virtual?
Try to project it on a screen.

13. #12
What happens to a narrow light beam that enters parallel to the principal axis of a spherical concave mirror?
It passes through the focal point.

14. #13
What happens to a narrow light beam that passes through the focal point of a concave mirror before being reflected?
It reflects back parallel to the principal axis.

15. #14
If a vehicle 2.0 m high is 4.6 m from a car’s convex mirror, find the position and height of the image, given that the radius of curvature is 0.80 m.
Q= m, h’-0.16 m

16. #15
Which of the following does not refer to a type of electromagnetic wave? A. radio B. sonar C. ultraviolet D. X-ray E. microwave F. gamma B.

17. #16
The wavelength of red light is _?_ that of blue light; the frequency of red light is _?_ that of blue light. A. longer than; higher than B. shorter than; lower than C. longer than; lower than D. longer than; the same as E. the same as; higher than F. none of these C.

18. #17
From lowest to highest frequency, these would be ordered A. R-IR-UV-γ B. IR-R-UV-γ C. γ-IR-UV-R D. UV-IR-γ-R E. IR-γ-R-UV F. γ-UV-IR-R G. R-UV-γ-IR H. UV-R-IR-γ A.

19. #18
Which station broadcasts with 2.94m radio waves? A. KXPR 91.7MHz B. Y 92.5MHz C. WGRD 98.5MHz D. KSFM 102MHz E. KWOD 106MHz F. WLAV 108MHz D.

20. #19
A thimble is 32.0 cm from a concave mirror. The focal point of the mirror is 11.0 cm. What is the magnification of the image?
M = -0.52

21. #20
A child who is 1.1 m tall is standing 6.0 m from a convex mirror. The child’s image is 0.40 m behind the mirror. What is the size of the image?
Height of image is m

22. #21 What does negative value of focal length tell you about a mirror?
What does a negative image distance tell you about an image?
The mirror is convex. The image is virtual.

23. #22
Describe how an image would change as an object is moved from very far away towards the surface of a concave mirror.
It would start of real, inverted, and reduced. As you approach C, it stays the same but gets larger. At C, h=h’. Between C and F the image is real, enlarged, and inverted…it is located beyond C. At F, no image is formed. Within F, the image is virtual, upright, and enlarged.

24. #23 What does the law of reflection state?
Angle of incidence = angle of reflection

25. #24
Which color of the visible light portion of the electromagnetic spectrum has the highest frequency?
Most energy?
Longest wavelength?
Violet, violet, red

26. #25
A laser pointer emits light waves with a wavelength of 533 nm. What is the frequency of this light?
5.6 E 14 Hz