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Skills Worksheet
Critical Thinking
Now You See It, Now You Don’t
Prime Time Interviews
Announcer: Captain Reginald P. Nutt, hero and explorer, has
just returned from an expedition in the Sahara Desert. We are fortunate
enough to conduct the first live interview with him.
Kara Little: Captain P. Nutt, I understand that you did not finish your journey across the Sahara.
Captain P. Nutt: Quite right. If it weren’t for those pesky mirages, I would
have completed the journey.
Kara Little: Optical illusions kept you from finishing your expedition?
Captain P. Nutt: It may sound silly, but imagine constantly seeing pools of
water in a hot desert only to find out there really is no water. It is enough to
drive anyone nuts!
Kara Little: What causes these illusions?
Captain P. Nutt: Changes in air temperature cause changes in air density.
Mirages are caused when light is bent as it passes through layers of air that
have different densities. I’ve also seen mirages in extremely cold places,
like Antarctica.
Kara Little: Well, that’s all the time we have today. Tune in next week
for more.
USEFUL TERMS
mirage an optical illusion in which a distant object appears to be nearby
optical illusion something which deceives the eye by false or unreal appearances
COMPREHENDING IDEAS
1. Is light refracted when you see a mirage? Explain your answer.
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Critical Thinking continued
2. Captain P. Nutt claims to have seen mirages in extremely cold climates. Do
you think this is possible? Why or why not?
MAKING COMPARISONS
3. The refraction of light causes many interesting visual displays, including
rainbows. How is the formation of a rainbow different from the formation of a
mirage?
4. Objects sometimes appear bent or disconnected when they are partially
placed in water. How is the formation of this illusion similar to the formation
of a mirage?
DEMONSTRATING REASONED JUDGMENT
5. Captain P. Nutt is planning his next scientific expedition to the forests and
swamps of Louisiana. Give two reasons why he might not see mirages there.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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TEACHER RESOURCE PAGE
17.
18.
19.
20.
21.
Diffraction: a change in the direction of a
wave when the wave finds an obstacle
or an edge, such as an opening. Example:
Shadows appear slightly blurry at
the edges.
Interference: the combination of two or
more waves that results in a single
wave. Example: When light of one wavelength shines through two slits onto a
screen a series of bright and dark bands
will appear.
FIONA, PRIVATE EYE
1. a. normal; b. angle of incidence;
c. reflected beam; d. incident beam;
e. angle of reflection
Light
source
Normal
Incident
beam
Reflected
beam
Angle of incidence
Angle of reflection
Mirror
2.
_
_
_
_
22.
Refraction: the bending of a wave as the
wave passes between two substances in
which the speed of the wave differs.
Example: a straw placed in a glass of
water appears bent.
_
16.
Scattering: an interaction of light with
matter that causes light to change its
energy, direction of motion, or both.
Example: Scattering of blue light makes
the sky look blue.
_
15.
A
C
B
D
C
Gamma rays are used to treat some
forms of cancer and are used to kill
harmful bacteria in foods.
Two uses for radio waves are the
broadcasting of radio signals and the
broadcasting of television signals.
Frost is translucent, so the light
traveling through it is scattered as it
passes through.
time distance speed time;
time 54,900,000 km 300,000 km/s;
time 183 s (or 3.05 min)
An answer to this exercise can be
found at the end of this book.
The tern sees the fish in the wrong
place because light refracts as it
passes from the water to the air. This
creates an optical illusion for the tern.
My brother’s conclusion is wrong
because he is confusing mixing of light
(color addition) with mixing of
pigments (color subtraction).
Sunshades keep the interior of cars
from getting very hot because sunshades reflect light that is transmitted
through the glass window of the car.
The light reflects back out the window, so the light cannot warm the air
or seats inside the car.
a. refraction; b. absorption and
scattering; c. reflection
_
9.
10.
11.
12.
13.
14.
____
_
Reinforcement
_
LIGHT INTERACTIONS
_
_
_
_
_
Absorption: in optics, the transfer of light
energy to particles of matter. Example:
Due to absorption (and scattering), the
beam of a flashlight appears dimmer the
further it is from the flashlight.
_
Answers will vary. Sample answers:
Reflection: the bouncing back of a ray of
light, sound, or heat when the ray hits a
surface that it does not go through.
Example: A green sweater looks green
because green light is reflected off it.
_
Back
Fiona
Jorge Charles Tamika
wall
3. Fiona can see Jorge.
Critical Thinking
1. Yes; light rays bend as they pass
through air layers of different densities
because the speed of light changes.
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TEACHER RESOURCE PAGE
2. Sample answer: Yes, it is possible
because the temperature of the ground
is colder than the air above it, creating
air layers of different densities. The
light is bent as it passes through the
different layers and can create a
mirage.
3. Sample answer: Rainbows are formed
when light is refracted by water
droplets instead of through layers of
air, as in a desert mirage.
4. Sample answer: Both are formed by
the refraction of light as it passes
through mediums of different densities. An object appears bent in water
because light bends as it passes from
air to water. A mirage appears when
light is bent as it passes through air
layers of different densities.
5. Sample answer: The temperatures in
this area are not extreme enough to
cause the changes in air density
required for mirages. In addition, the
trees may block the sunlight that is
needed to create a mirage.
Section Quizzes
SECTION: WHAT IS LIGHT?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
B
C
A
D
B
A
D
A
D
B
SECTION: THE ELECTROMAGNETIC
SPECTRUM
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
D
C
B
F
E
G
A
D
C
A
SECTION: INTERACTIONS OF LIGHT
WAVES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
A
F
D
E
B
C
C
D
A
B
SECTION: LIGHT AND COLOR
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
D
E
A
C
B
C
B
A
A
B
Chapter Test A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
C
C
D
C
E
F
A
B
C
D
G
E
F
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
D
A
B
C
G
C
A
B
A
C
B
C
Chapter Test B
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
scattering
opaque
absorption
interference
transparent
B
A
D
A
D
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Science and Technology
127
The Nature of Light