Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Is it possible to see a virtual image?
1)
A) No, since the rays that seem to emanate from a virtual image do not in fact emanate from the
image.
B) Yes, but only indirectly in the sense that if the virtual image is formed on a sheet of
photographic film, one could later look at the picture formed.
C) Yes, since almost everything we see is virtual because most things do not themselves give off
light, but only reflect light coming from some other source.
D) Yes, the rays that appear to emanate from a virtual image can be focused on the retina just like
those from an illuminated object.
E) No, since virtual images do not really exist.
2) A spherical mirror on which reflection takes place on the outer surface of the spherical shape is
referred to as a
A) concave mirror.
2)
B) convex mirror.
3) A spherical mirror on which reflection takes place on the inner surface of the sphere is referred to
as a
A) concave mirror.
3)
B) convex mirror.
4) If the radius of curvature of the concave mirror is r, the focal length is
4)
A) r/2.
B) r.
C) 2r.
D) cannot be determined from the information given
5) A light ray, traveling parallel to a concave mirror's axis, strikes the mirror's surface near its
midpoint. After reflection, this ray
5)
A) passes through the mirror's focal point.
B) passes through the mirror's center of curvature.
C) again travels parallel to the mirror's axis.
D) travels at right angles to the mirror's axis.
6) Light arriving at a concave mirror on a path through the center of curvature is reflected
A) through the focal point.
B) back parallel to the axis.
C) back on itself.
D) midway between the focal point and the center of curvature.
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6)
7) A light ray, traveling obliquely to a concave mirror's surface, crosses the axis at the mirror's focal
point before striking the mirror's surface. After reflection, this ray
7)
A) travels at right angles to the mirror's axis.
B) travels parallel to the mirror's axis.
C) passes through the mirror's center of curvature.
D) passes through the mirror's focal point.
8) Light arriving at a concave mirror on a path through the focal point is reflected
A) through the focal point.
B) back on itself.
C) through the center of curvature.
D) back parallel to the axis.
8)
ESSAY. Write your answer in the space provided or on a separate sheet of paper.
9) State how to draw the three rays for finding the image position due to a curved mirror.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
10) If you stand in front of a concave mirror, exactly at its focal point,
10)
A) you will see your image and you will appear larger.
B) you will see your image, and you will appear smaller.
C) you won't see your image because it's focused at a different distance.
D) you won't see your image because there is none.
E) you will see your image at your same height.
11) If you stand in front of a convex mirror, at the same distance from it as its radius of curvature,
11)
A) you will see your image and you will appear smaller.
B) you will see your image and you will appear larger.
C) you won't see your image because it's focused at a different distance.
D) you will see your image at your same height.
E) you won't see your image because there is none.
12) If you stand in front of a convex mirror, at the same distance from it as its focal length,
A) you will see your image and you will appear larger.
B) you won't see your image because there is none.
C) you will see your image and you will appear smaller.
D) you will see your image at your same height.
E) you won't see your image because it's focused at a different distance.
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12)
13) Sometimes when you look into a curved mirror you see a magnified image (a great big you) and
sometimes you see a diminished image (a little you). If you look at the bottom (convex) side of a
shiny spoon, what will you see?
13)
A) You will see a little you, but whether you are right side up or upside down depends on how
near you are to the spoon.
B) You will see a little you, right side up.
C) You will see a little you, upside down.
D) You won't see an image of yourself because no image will be formed.
E) You will either see a little you or a great big you, depending on how near you are to the spoon.
14) Concave spherical mirrors produce images which
14)
A) are always larger than the actual object.
B) could be smaller than, larger than, or the same size as the actual object, depending on the
placement of the object.
C) are always the same size as the actual object.
D) are always smaller than the actual object.
15) If the magnification is a positive value, the image is
15)
A) inverted.
B) upright.
16) If the magnification is a negative value, the image is
A) inverted.
16)
B) upright.
17) If the absolute value of the magnification is larger than one, then the image is
17)
A) smaller than the object.
B) the same size as the object.
C) larger than the object.
18) The index of refraction of diamond is 2.42. This means that a given frequency of light travels
18)
A) 2.42 times faster in air than it does in diamond.
B) 2.42 times faster in vacuum than it does in diamond.
C) 2.42 times faster in diamond than it does in air.
D) 2.42 times faster in diamond than it does in vacuum.
19) Light traveling at an angle into a denser medium is refracted
A) parallel to the normal.
B) equally.
C) toward the normal.
D) away from the normal.
20) Light enters air from water. The angle of refraction will be
A) greater than the angle of incidence.
B) less than the angle of incidence.
C) equal to the angle of incidence.
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19)
20)
21) A ray of light, which is traveling in air, is incident on a glass plate at a 45e angle. The angle of
refraction in the glass
21)
A) is equal to 45e .
B) is greater than 45e.
C) is less than 45e .
D) could be any of the above; it all depends on the index of refraction of glass.
22) Lenses that are thinner at the center than the edges are called
A) converging lenses.
22)
B) diverging lenses.
23) Lenses that are thicker at the center
23)
A) have no effect on light rays.
B) spread out light rays.
C) reflect light rays back.
D) bend light rays to a point beyond the lens.
24) A laser beam strikes a plane's reflecting surface with an angle of incidence of 52e. What is the angle
between the incident ray and the reflected ray?
A) 90e
B) 45e
C) 105 e
D) 52e
25) An object is located 2.6 m in front of a plane mirror. The image formed by the mirror appears to be
A) 1.3 m behind the mirror's surface.
B) 1.3 m in front of the mirror.
C) 2.6 m behind the mirror's surface.
D) on the mirror's surface.
26) How far are you from your image when you stand 0.75 m in front of a vertical plane mirror?
A) 0.75 m
B) 3.0 m
C) 1.5 m
D) none of the given answers
27) How fast do you approach your image when you approach a vertical plane mirror at a speed of 2
m/s?
A) 4 m/s
B) 2 m/s
C) 1 m/s
D) none of the given answers
28) A spherical concave mirror has a radius of curvature of 20 cm. How far from the mirror is the focal
point located?
A) 40 cm
B) 20 cm
C) 10 cm
B) 7.0 cm from the mirror
C) 13 cm from the mirror
D) 3.3 cm from the mirror
30) A concave spherical mirror has a focal length of 20 cm. An object is placed 10 cm in front of the
mirror on the mirror's axis. Where is the image located?
A) 20 cm behind the mirror
B) 20 cm in front of the mirror
C) 6.7 cm in front of the mirror
D) 6.7 cm behind the mirror
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25)
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D) 30 cm
29) An object is 10 cm in front of a concave mirror with focal length 3 cm. Where is the image?
A) 4.3 cm from the mirror
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29)
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31) A concave spherical mirror has a focal length of 20 cm. An object is placed 30 cm in front of the
mirror on the mirror's axis. Where is the image located?
A) 60 cm behind the mirror
B) 12 cm in front of the mirror
C) 12 cm behind the mirror
D) 60 cm in front of the mirror
32) An object is 5.7 cm from a concave mirror. The image is 4.7 cm tall, and 10 cm from the mirror.
How tall is the object?
A) 2.7 cm
B) 8.2 cm
C) 12 cm
B) 16 cm
C) 2.0 cm
B) 12.0 cm
C) 18.2 cm
A) 12 cm in front of the mirror
B) 12 cm behind the mirror
C) 60 cm behind the mirror
D) 60 cm in front of the mirror
36) When a person stands 40 cm in front of a cosmetic mirror (concave mirror), the erect image is twice
the size of the object. What is the focal length of the mirror?
B) 160 cm
C) 40 cm
B) 20 cm
C) 90 cm
A) 1.0 cm behind the mirror
B) 2.2 cm behind the mirror
C) 2.2 cm in front of the mirror
D) 9.0 cm in front of the mirror
39) An object is 14 cm in front of a convex mirror. The image is 5.8 cm behind the mirror. What is the
focal length of the mirror?
B) -8.2 cm
C) -20 cm
B) -13.0 cm
C) -16.9 cm
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37)
38)
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D) -4.1 cm
40) An object is 8.90 cm tall. The image is 7.80 cm tall, and 14.8 cm from a convex mirror. What is the
mirror's focal length?
A) -120 cm
36)
D) 70 cm
38) An image is 4.0 cm behind a concave mirror with focal length 5.0 cm. Where is the object?
A) -9.9 cm
35)
D) 27 cm
37) A person's face is 30 cm in front of a concave shaving mirror. If the image is an erect image 1.5
times as large as the object, what is the mirror's focal length?
A) 50 cm
34)
D) 47.6 cm
35) An object is placed 15 cm from a concave mirror of focal length 20 cm. The object is 4.0 cm tall.
Where is the image located?
A) 80 cm
33)
D) 1.0 cm
34) An object is 47.5 cm tall. The image is 38.6 cm tall, and 14.8 cm from the mirror. How far is the
object from the mirror?
A) 124 cm
32)
D) 11 cm
33) An object is placed 15 cm from a concave mirror of focal length 20 cm. The object is 4.0 cm tall.
How tall is the image?
A) 8.0 cm
31)
D) -105 cm
40)
Answer Key
Testname: GEOMETRIC OPTICS_PRACTICE QUIZ_05.01.13
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D
B
A
A
A
C
B
D
Ray 1 leaves the top of the object and is drawn such that it is parallel to the axis; therefore after reflection it must pass
along a line through the focal point.
Ray 2 leaves the top of the object and is made to pass through the focal point; therefore it must reflect so it is parallel to
the axis.
Ray 3 leaves the top of the object and is made to pass through the center of curvature; therefore it must reflect back on
itself.
D
A
C
B
B
B
A
C
B
C
A
C
B
D
C
C
C
A
C
A
A
D
A
B
C
C
A
C
C
A
A
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