Section 18.1
Refraction of Light
Practice Test
1.
A ray of sunlight travels through air and intersects the surface of water at a small incident angle. The ray is __________.
a.
pure
b.
refracted
c.
reflected
d.
incident
Hint
2.
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.
Hint
3.
What is dispersion?
a.
the reflection of colored light
b.
the refraction of light
c.
the separation of light into its spectrum
d.
the combining of colored light into white light
Hint
4.
In relation to a rainbow that you are looking at, where is the Sun?
a.
directly overhead
b.
behind you
c.
in front of you
d.
in the center of the rainbow
Hint
5.
According to Snell's law, light traveling from a vacuum to glass will __________.
a.
slow down
b.
stop completely
c.
travel at the same speed
d.
speed up
Hint
6.
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.
0.985
c.
1.66
d.
2.00
Hint
7.
How is information carried in an optical fiber?
a.
by light
b.
by sound
c.
by electrical impulses
d.
by different colors
Hint
8.
Optical fibers are a technical application of __________.
a.
diffraction
b.
dispersion
c.
refraction
d.
total internal reflection
Hint
9.
In Figure 18-1a, 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.
a.
22°
b.
68°
c.
57°
d.
35°
Hint
10.
Water is more optically dense than air. Therefore, the speed of light in water is __________.
a.
the same as the speed of light in air
b.
the same as the speed of light in a vacuum
c.
faster than the speed of light in air
d.
slower than the speed of light in air
Hint
11.
Why would it be impossible to have optical fibers filled with a vacuum?
a.
because optical fibers must use glass
b.
there is nothing less optically dense than a vacuum
c.
there is nothing for light to travel through
d.
because a vacuum is too optically dense
Hint
12.
A ray of light striking perpendicular to an optically dense surface will __________.
a.
remain straight
b.
reflect
c.
refract away from the normal
d.
refract toward the normal
Hint
13.
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.
less than
b.
unrelated to
c.
greater than
d.
the same as
Hint
14.
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.
0.709
b.
1.81
c.
0.643
d.
1.20
Hint
15.
What is the speed of light in a diamond (
n
= 2.42)?
a.
1.24×10
8
m/s
b.
3.00×10
8
m/s
c.
2.42×10
8
m/s
d.
7.26×10
8
m/s
Hint
16.
What does Snell's law compare?
a.
the density of the materials
b.
the sines of the refracted angles
c.
the cosines of the refracted angles
d.
the reflective nature of materials
Hint
17.
For the situation shown in Figure 18-1b, which of the substances listed below should be chosen to put in front of the pencil to make its "break" the most pronounced?
a.
vacuum
b.
water
c.
flint glass
d.
ethanol
Hint
18.
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 refracted.
b.
It is reflected.
c.
It is stopped.
d.
It is diffused.
Hint
19.
Because of refraction, the Sun actually sets __________ we see it disappear.
a.
after
b.
at the same time as
c.
before
d.
hours before
Hint
20.
The incident angle that causes a refracted ray to lie along the boundary of a substance is the __________.
a.
refracted angle
b.
critical angle
c.
normal angle
d.
reflected angle
Hint
21.
Through which medium is the speed of light the fastest?
a.
water
b.
vacuum
c.
glass
d.
air
Hint
22.
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.
0.433°
b.
33.0°
c.
25.7°
d.
0.839°
Hint
23.
What causes a mirage?
a.
water on the ground
b.
heatstroke
c.
a continuous change in the index of refraction of air because
n
increases as air gets warmer
d.
a continuous change in the index of refraction of air because
n decreases as air gets warmer
Hint
