Physics Principles and Problems 2009

Chapter 18: Refraction and Lenses

Chapter Test Practice

1
How is information carried in an optical fiber?
A)by sound
B)by different colors
C)by electrical impulses
D)by light
2

For the situation shown in the figure below, which of the substances listed below should be chosen to put in front of the pencil to make its "break" the most pronounced?

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A)flint glass
B)vacuum
C)ethanol
D)water
3
A light ray is traveling through an unknown material when it intersects ethanol (n = 1.36) at an incident angle of 62.0°. If the angle of refraction is 46.4°, what is the index of refraction of the unknown material?
A)1.12
B)1.66
C)0.985
D)2
4
If a refracted ray moves away from the normal, the speed of light of the ray in this material is __________ that of the incident ray.
A)unrelated to
B)less than
C)greater than
D)the same as
5
If a substance has a critical angle of 50°, what happens to the light from an incident angle hitting the boundary at 30°?
A)It is stopped.
B)It is reflected.
C)It is diffused.
D)It is refracted.
6
What is dispersion?
A)the separation of light into its spectrum
B)the refraction of light
C)the combining of colored light into white light
D)the reflection of colored light
7
The incident angle that causes a refracted ray to lie along the boundary of a substance is the __________.
A)refracted angle
B)reflected angle
C)critical angle
D)normal angle
8
What is the speed of light in a diamond (n = 2.42)?
A)2.42×108 m/s
B)1.24×108 m/s
C)7.26×108 m/s
D)3.00×108 m/s
9
Why would it be impossible to have optical fibers filled with a vacuum?
A)there is nothing for light to travel through
B)there is nothing less optically dense than a vacuum
C)because a vacuum is too optically dense
D)because optical fibers must use glass
10
A light ray traveling through crown glass (n = 1.52) intersects a sheet of flint glass (n = 1.61) at an angle of 27.3°. What is the angle of refraction?
A)0.839°
B)33.0°
C)25.7°
D)0.433°
11
In relation to a rainbow that you are looking at, where is the Sun?
A)in the center of the rainbow
B)behind you
C)directly overhead
D)in front of you
12
Water is more optically dense than air. Therefore, the speed of light in water is __________.
A)the same as the speed of light in a vacuum
B)slower than the speed of light in air
C)faster than the speed of light in air
D)the same as the speed of light in air
13
According to Snell's law, light traveling from a vacuum to glass will __________.
A)speed up
B)travel at the same speed
C)stop completely
D)slow down
14
Because of refraction, the Sun actually sets __________ we see it disappear.
A)after
B)before
C)at the same time as
D)hours before
15
A beam of light travels through air (n = 1.0003) and strikes an unknown material at an angle of 50.0°. The new angle of refraction is 25.0°. What is the index of refraction of this material?
A)0.643
B)1.2
C)1.81
D)0.709
16
What happens to light during total internal reflection?
A)The angle of refraction is less than the critical angle.
B)The angle of incidence is greater than the critical angle.
C)The angle of incidence is 0.
D)The angle of reflection is the same as the critical angle.
17
Optical fibers are a technical application of __________.
A)diffraction
B)dispersion
C)total internal reflection
D)refraction
18
A ray of light striking perpendicular to an optically dense surface will __________.
A)refract away from the normal
B)reflect
C)refract toward the normal
D)remain straight
19
A ray of sunlight travels through air and intersects the surface of water at a small incident angle. The ray is __________.
A)pure
B)reflected
C)refracted
D)incident
20
What causes a mirage?
A)heatstroke
B)a continuous change in the index of refraction of air because n increases as air gets warmer
C)water on the ground
D)a continuous change in the index of refraction of air because n decreases as air gets warmer
21

In the figure below, if the incident angle is 35°, what is the angle of refraction in the glass? Use 1.55 for the index of refraction of glass.

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A)35°
B)68°
C)57°
D)22°
22
Through which medium is the speed of light the fastest?
A)air
B)water
C)vacuum
D)glass
23
What does Snell's law compare?
A)the reflective nature of materials
B)the cosines of the refracted angles
C)the density of the materials
D)the sines of the refracted angles
24

In the figure below, if the bottom half of the lens is covered, what will happen to the image?

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A)Nothing.
B)The bottom half of the image will disappear
C)The top half of the image will disappear.
D)The image will become dimmer.
25

In the figure below, if the top half of the lens is covered, what will happen to the image?

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A)The top half of the image will disappear.
B)The bottom half of the image will disappear
C)Nothing.
D)The image will become dimmer.
26
An image of a flower is seen through a lens. What is the object?
A)a flower
B)an image
C)a lens
D)a mirror
27
The refractive indices of lenses are __________.
A)the same as air
B)less than air
C)independent of the refractive index of air
D)greater than air
28
The focal length of a concave lens is __________.
A)negative
B)reduced
C)magnified
D)positive
29
A concave lens is also known as a __________ lens
A)concave
B)converging
C)diverging
D)plane
30

In the figure below, if you wanted to make the virtual image larger, what could you do?

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A)Move the object further out, but not past the focal point.
B)Replace the object with a shorter object.
C)Replace the lens with one of larger focal length.
D)Replace the lens with a taller one.
31
Why are bigger lenses better for observing dim objects?
A)they have better curvatures
B)they refract light less
C)they collect more light
D)they reduce spherical aberration
32
Unlike mirrors, lenses have __________.
A)one focal point
B)no focal points
C)many focal points
D)two focal points
33
An achromatic lens corrects chromatic aberration using __________.
A)two convex lenses with the same index of refraction
B)a combination of concave and convex lenses with different indices of refraction
C)two concave lenses with the same index of refraction
D)no lenses
34
__________ single lenses have chromatic aberration.
A)Only parabolic
B)Only concave
C)Only convex
D)All
35
In nearsightedness, the image is focused __________.
A)in front of the retina
B)beyond the retina
C)directly on the retina
D)in front of the eye
36
Farsightedness can be corrected with a __________.
A)parabolic lens
B)convex lens
C)concave lens
D)plane lens
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