Section 18.1
Refraction of Light
Practice Test
1.
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.
ethanol
c.
flint glass
d.
water
Hint
2.
A ray of sunlight travels through air and intersects the surface of water at a small incident angle. The ray is __________.
a.
refracted
b.
reflected
c.
incident
d.
pure
Hint
3.
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.
57°
b.
35°
c.
22°
d.
68°
Hint
4.
Through which medium is the speed of light the fastest?
a.
vacuum
b.
air
c.
water
d.
glass
Hint
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 refracted.
d.
It is diffused.
Hint
6.
Water is more optically dense than air. Therefore, the speed of light in water is __________.
a.
faster than the speed of light in air
b.
slower than the speed of light in air
c.
the same as the speed of light in air
d.
the same as the speed of light in a vacuum
Hint
7.
In relation to a rainbow that you are looking at, where is the Sun?
a.
directly overhead
b.
in the center of the rainbow
c.
in front of you
d.
behind you
Hint
8.
Why would it be impossible to have optical fibers filled with a vacuum?
a.
there is nothing less optically dense than a vacuum
b.
there is nothing for light to travel through
c.
because a vacuum is too optically dense
d.
because optical fibers must use glass
Hint
9.
What happens to light during total internal reflection?
a.
The angle of incidence is 0.
b.
The angle of incidence is greater than the critical angle.
c.
The angle of refraction is less than the critical angle.
d.
The angle of reflection is the same as the critical angle.
Hint
10.
What does Snell's law compare?
a.
the reflective nature of materials
b.
the density of the materials
c.
the cosines of the refracted angles
d.
the sines of the refracted angles
Hint
11.
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.
25.7°
c.
0.839°
d.
33.0°
Hint
12.
According to Snell's law, light traveling from a vacuum to glass will __________.
a.
travel at the same speed
b.
speed up
c.
slow down
d.
stop completely
Hint
13.
Because of refraction, the Sun actually sets __________ we see it disappear.
a.
before
b.
hours before
c.
at the same time as
d.
after
Hint
14.
What is the speed of light in a diamond (
n
= 2.42)?
a.
7.26×10
8
m/s
b.
3.00×10
8
m/s
c.
1.24×10
8
m/s
d.
2.42×10
8
m/s
Hint
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.
1.20
c.
0.709
d.
1.81
Hint
16.
The incident angle that causes a refracted ray to lie along the boundary of a substance is the __________.
a.
reflected angle
b.
critical angle
c.
refracted angle
d.
normal angle
Hint
17.
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.
the same as
b.
less than
c.
unrelated to
d.
greater than
Hint
18.
How is information carried in an optical fiber?
a.
by electrical impulses
b.
by light
c.
by sound
d.
by different colors
Hint
19.
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
20.
What causes a mirage?
a.
heatstroke
b.
a continuous change in the index of refraction of air because
n decreases as air gets warmer
c.
water on the ground
d.
a continuous change in the index of refraction of air because
n
increases as air gets warmer
Hint
21.
Optical fibers are a technical application of __________.
a.
total internal reflection
b.
refraction
c.
dispersion
d.
diffraction
Hint
22.
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.
0.985
b.
1.66
c.
2.00
d.
1.12
Hint
23.
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
Hint
