# Unit 13 Review

1. As the angle of incidence is increased for a ray incident on a reflecting surface, the angle between the incident and reflected rays ultimately approaches what value?

 a. zero b. 45 degrees c. 90 degrees d. 180 degrees

The Law of Reflection (7 seconds)

2. If you stand three feet in front of a plane mirror, how far away would you see yourself in the mirror?

 a. 1.5 ft b. 3.0 ft c. 6.0 ft d. 12.0 ft

Image Characteristics for Plane Mirrors (6 seconds)

3. A concave mirror with a focal length of 10 cm creates a real image 30 cm away on its principal axis; the corresponding object is located how far from the mirror?
 a. 20.0 cm b. 15.0 cm c. 7.5 cm d. d. 5.0 cm

The Mirror Equation - Concave Mirrors (6 seconds)

4. A concave mirror forms a real image at 25 cm from the mirror surface along the principal axis. If the corresponding object is at a 10 cm distance, what is the mirror's focal length?

 a. 1.4 cm b. 16.7 cm c. 12.4 cm d. 7.1 cm

The Mirror Equation - Concave Mirrors (6 seconds) | Image Characteristics for Concave Mirrors (9 seconds)

5. If a virtual image is formed along the principal axis 10 cm from a concave mirror with the focal length 15 cm, what is the object distance from the mirror?

 a. 30.0 cm b. 10.0 cm c. 12.4 cm d. 6.0 cm

The Mirror Equation - Concave Mirrors (6 seconds) | Image Characteristics for Concave Mirrors (9 seconds)

6. If a virtual image is formed 10 cm along the principal axis from a convex mirror of focal length -15 cm, what is the object distance from the mirror?

 a. 30.0 cm b. 10.0 cm c. 6.0 cm d. 3.0 cm

Image Characteristics for Convex Mirrors (7 seconds) | The Mirror Equation - Convex Mirrors (5 seconds)

7. If a man's face is 30 cm in front of a concave shaving mirror creating an upright image 1.5 times as large as the object, what is the mirror's focal length?

 a. 12.0 cm b. 20.0 cm c. 70.0 cm d. 90.0 cm

The Mirror Equation - Concave Mirrors (6 seconds) | Image Characteristics for Concave Mirrors (9 seconds)

8. Which of the following best describes the image of a plane mirror?

1. virtual, inverted and enlarged
2. real, inverted and reduced
3. virtual, upright and the same size as object
4. real, upright and the same size as object

Image Characteristics for Plane Mirrors (6 seconds)

9. Which of the following best describes the image of a concave mirror when the object is located somewhere between the focal point (F) and the center of curvature (C) of the mirror?

 a. virtual, upright and enlarged b. real, inverted and reduced c. virtual, upright and reduced d. real, inverted and enlarged

The Anatomy of a Curved Mirror (6 seconds)

10. Which of the following best describes the image of a concave mirror when the object is at a distance further than the center of curvature (C) of the mirror?

 a. virtual, erect and enlarged b. real, inverted and reduced c. virtual, upright and reduced d. real, inverted and enlarged

Ray Diagrams - Concave Mirrors (14 seconds) | Image Characteristics for Concave Mirrors (9 seconds)

11. Which of the following best describes the image of a concave mirror when the object distance from the mirror is less than the focal point (F) distance?

 a. virtual, upright and enlarged b. real, inverted and reduced c. virtual, upright and reduced

Ray Diagrams - Concave Mirrors (14 seconds) | Image Characteristics for Concave Mirrors (9 seconds)

12. Which of the following best describes the image of a convex mirror when the object distance from the mirror is less than the absolute value of the focal point (F) distance?

 a. virtual, upright and enlarged b. real, inverted and reduced c. virtual, upright and reduced d. real, inverted and enlarged

Ray Diagrams - Convex Mirrors (8 seconds) | Image Characteristics for Convex Mirrors (7 seconds)

13. Use of a parabolic mirror, instead of one made of a circular arc surface, can be used to reduce the occurrence of which of the following effects?

 a. spherical aberration b. mirages c. chromatic aberration d. light scattering

Spherical Aberration (6 seconds)

14. When the image of an object is seen in a plane mirror, the image is

 a. real and upright. b. real and inverted. c. virtual and upright. d. virtual and inverted.

Image Characteristics for Plane Mirrors (6 seconds)

15. When the image of an object is seen in a plane mirror, the distance from the mirror to the image depends on

1. the wavelength of light used for viewing.
2. the distance from the object to the mirror.
3. the distance of both the observer and the object to the mirror.

Image Characteristics for Plane Mirrors (6 seconds) | Ray Diagrams for Plane Mirrors (11 seconds)

16. If a man wishes to use a plane mirror on a wall to view both his head and his feet as he stands in front of the mirror, the required length of the mirror

1. is equal to the height of the man.
2. is equal to one half the height of the man.
3. depends on the distance the man stands from the mirror.
4. depends on both the height of the man and the distance from the man to the mirror.

What Portion of a Mirror is Required to View an Image? (7 seconds)

17. When the image of an object is seen in a concave mirror the image will

 a. always be real. b. always be virtual. c. be either real or virtual. d. will always be magnified.

Image Characteristics for Concave Mirrors (9 seconds)

18. When the image of an object is seen in a convex mirror the image will

 a. always be real. b. always be virtual. c. may be either real or virtual. d. will always be magnified.

Image Characteristics for Convex Mirrors (7 seconds)

19. Rays of light traveling parallel to the principal axis of a concave mirror will come together

 a. at the center of curvature. b. at the focal point. c. at infinity. d. at a point half way to the focal point.

Reflection of Light and Image Formation (6 seconds)

20. If carbon tetrachloride has an index of refraction of 1.461, what is the speed of light through this liquid? (c = 3 x 10^8 m/s)

 a. 4.38 x 10^8 m/s b. 2.05 x 10^8 m/s c. 4.461 x 10^8 m/s d. 1.461 x 10^8 m/s

Optical Density and Light Speed (13 seconds)

21. A ray of light in air is incident on an air-to-glass boundary at an angle of 30 degrees with the normal. If the index of refraction of the glass is 1.65, what is the angle of the refracted ray within the glass with respect to the normal?

 a. 56 degrees b. 46 degrees c. 30 degrees d. 18 degrees

Snell's Law (10 seconds) | Ray Tracing and Problem-Solving (15 seconds)

22. If the critical angle for internal reflection inside a certain transparent material is found to be 48 degrees, what is the index of refraction of the material? (Air is outside the material).

 a. 1.35 b. 1.48 c. 1.49 d. 0.743

The Critical Angle (10 seconds)

23. Carbon disulfide (n = 1.63) is poured into a container made of crown glass (n = 1.52). What is the critical angle for internal reflection of a ray in the liquid when it is incident on the liquid-to-glass surface?

 a. 89 degrees b. 69 degrees c. 21 degrees d. 4.0 degrees

The Critical Angle (10 seconds)

24. Carbon tetrachloride (n = 1.46) is poured into a container made of crown glass (n = 1.52). If the light ray in glass incident on the glass-to-liquid boundary makes an angle of 30 degrees with the normal, what is the angle of the corresponding refracted ray with respect to the normal?

 a. 55.5 degrees b. 29.4 degrees c. 31.4 degrees d. 19.2 degrees

Snell's Law (10 seconds) | Ray Tracing and Problem-Solving (15 seconds)

25. A light ray in air is incident on an air to glass boundary at an angle of 45 degrees and is refracted in the glass of 30 degrees with the normal. What is the index of refraction of the glass?
 a. 2.13 b. 1.74 c. 1.23 d. 1.41

Determination of n Values (10 seconds)

26. A beam of light in air is incident at an angle of 35 degrees to the surface of a rectangular block of clear plastic (n = 1.49). The light beam first passes through the block and re-emerges from the opposite side into air at what angle to the normal to that surface?
 a. 42 degrees b. 23 degrees c. 35 degrees d. 59 degrees

Snell's Law (10 seconds) | Ray Tracing and Problem-Solving (15 seconds)

27. A light ray in air enters and passes through a block of glass. What can be stated with regard to its speed after it emerges from the block?

 a. speed is less than when in glass b. speed is less than before it entered glass c. speed is same as that in glass d. speed is same as that before it entered glass

Optical Density and Light Speed (13 seconds)

28. Which of the following describes what will happen to a light ray incident on an air-to-glass boundary?

 a. total reflection b. total transmission c. partial reflection, partial transmission d. partial reflection, total transmission

Boundary Behavior Revisited (5 seconds) | Total Internal Reflection (13 seconds)

29. Which of the following describes what will happen to a light ray incident on an air-to-glass boundary at less than the critical angle?

 a. total reflection b. total transmission c. partial reflection, partial transmission d. partial reflection, total transmission

Boundary Behavior Revisited (5 seconds) | Total Internal Reflection (13 seconds)

30. Which of the following describes what will happen to a light ray incident on an glass-to-air boundary at greater than the critical angle?

 a. total reflection b. total transmission c. partial reflection, partial transmission d. partial reflection, total transmission

Boundary Behavior Revisited (5 seconds) | Total Internal Reflection (13 seconds)

31. What is the angle of incidence on an air-to-glass boundary if the angle of refraction in the glass (n = 1.52) is 25 degrees?

 a. 16 degrees b. 25 degrees c. 40 degrees d. 43 degrees

Snell's Law (10 seconds) | Ray Tracing and Problem-Solving (15 seconds)

32. A ray of white light, incident upon a glass prism, is dispersed into its various color components. Which one of the following colors experiences the greatest amount of refraction?

 a. orange b. violet c. red d. green

33. When light from air hits a smooth piece of glass (n = 1.5) with the ray perpendicular to the glass surface, which of the following will occur?

 a. reflection and transmission at an angle of 0 degrees b. dispersion c. refraction at an angle of 41.8 degrees d. all of the above will occur

Boundary Behavior Revisited (5 seconds) | Total Internal Reflection (13 seconds)

34. When light from air hits a smooth piece of glass with the ray perpendicular to the glass surface, the part of the light passing into the glass

 a. will not change its speed b. will not change its direction c. will not change its wavelength d. will not change its intensity

The Secret of the Archer Fish (8 seconds)

35. If total internal reflection occurs at a glass-air surface,

1. no light is refracted
2. no light is reflected
3. light is leaving the air and hitting the glass with an incident angle greater than the critical angle
4. light is leaving the air and hitting the glass with an incident angle less than the critical angle

Total Internal Reflection (13 seconds)

36. Dispersion occurs when

1. some materials bend light more than other materials
2. a material slows down some colors more than others
3. a material changes some colors more than others
4. light has different speeds in different materials

37. A 3 cm tall object is placed along the principal axis of a thin converging lens of 30 cm focal length. If the object distance is 40 cm, which of the following best describes the image distance and height, respectively?

 a. 17.3 cm and 7.0 cm b. 120.0 cm and -9.0 cm c. 17.3 cm and 1.3 cm d. 120.0 cm and -1.0 cm

The Mathematics of Lenses (7 seconds)

38. Which of the following best describes the image for a thin converging lens that forms whenever the object is at a distance less than one focal length from the lens?

 a. inverted, enlarged and real b. upright, enlarged and virtual c. upright, reduced and virtual d. inverted, reduced and real

Ray Diagrams (15 seconds) | Object-Image Relations (9 seconds)

39. Which of the following best describes the image for a thin diverging lens that forms whenever the magnitude of the object distance is less than that of the lens' focal length?

 a. inverted, enlarged and real b. upright, enlarged and virtual c. upright, reduced and virtual d. inverted, reduced and real

Ray Diagrams (9 seconds) | Object-Image Relations (5 seconds)

40. An object is placed at a distance of 30 cm from a thin converging lens along its axis. The lens has a focal length of 10 cm. What are the values, respectively, of the image distance and magnification?

 a. 60 cm and 2.00 b. 15 cm and 2.00 c. 60 cm and -0.50 d. 15 cm and -0.50

The Mathematics of Lenses (7 seconds)

41. An object is placed at a distance of 6 cm from a thin converging lens along its axis. The lens has a focal length of 9 cm. What are the values, respectively, of the image distance and magnification?

 a. -18 cm and 3 b. 18 cm and 3 c. 3 cm and -0.5 d. -18 cm and -3

The Mathematics of Lenses (7 seconds)

42. An object is placed at a distance of 30 cm from a thin converging lens along the axis. If a real image forms at a distance of 10 cm from the lens, what is the focal length of the lens?

 a. 30 cm b. 15 cm c. 10 cm d. 7.5 cm

The Mathematics of Lenses (7 seconds)

43. An object is placed at a distance of 40 cm from a thin lens along the axis. If a virtual image forms at a distance of 50 cm from the lens, on the same side as the object, what is the focal length of the lens?

 a. 22 cm b. 45 cm c. 90 cm d. 200 cm

The Mathematics of Lenses (7 seconds)

44. Atmospheric refraction of light rays is responsible for which one of the following effects?

 a. spherical aberration b. mirages c. chromatic aberration d. light scattering

45. If atmospheric refraction did not occur, how would the apparent time of sunrise and sunset be changed?

 a. both would be later b. both would be earlier c. sunrise would be later and sunset earlier d. sunrise would be earlier and sunset later

46. Distinguish between diffuse and regular (specular) reflection in terms of both cause and result.

Specular vs. Diffuse Reflection (22 seconds)

 47. Consider the following object in front of a plane mirror. Construct a ray diagram to show how light tavels from the object (arrow) to the mirror and ultimately to the eye; then indicate the portion of the mirror needed in order for the eye to view the image.

Ray Diagrams for Plane Mirrors (11 seconds)

48. In the diagrams below, construct refracted rays to indicate the direction which the light rays bend upon crossing the boundary.
 If light travels faster in medium 1 than in medium 2, then upon entering medium 2, the light will bend towards from the normal. If the index of refraction of medium 1 is greater than medium 2, then upon entering medium 2, the light will bend away from the normal.

The Direction of Bending (20 seconds)

49. Construct ray diagrams to show where the images of the following objects are located. Dray in the complete image and describe its characteristics (real or virtual, enlarged or reduced in size, inverted or upright). (NOTE: review the ray diagrams for all possible objects locations for each device.)

 Concave Mirror: when the object is located between C and F, the image is an inverted real image located beyond C and magnified in size. Convex Mirrors produce upright virtual images located on the other side of the mirror which are reduced in size. Converging Lens: when the object is located beyond C, the image is an inverted real image located between C and F on the opposite side of the lens and reduced in size.

Ray Diagrams - Concave Mirrors (14 seconds) | Ray Diagrams - Convex Mirrors (8 seconds) | Converging Lenses - Ray Diagrams (15 seconds)