Waves PowerPoint
Waves PowerPoint
Waves PowerPoint
Table of
of Contents
Contents
Section 1: Waves
Section 3: Light
Waves
Waves
1
What are waves?
Answer
Waves carry energy, not matter. Think of what
happens when you shake one end of a rope; a
wave travels along the rope, but the rope itself
doesn’t move forward.
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Question 1
What is shown at point B in this illustration?
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A. crest
B. direction rope moves
C. direction wave moves
D. trough
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Answer
The answer is D. Low points on a wave are
called troughs.
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Question 3
The number of wavelengths that pass by each
second is the wave’s _______.
A. diffraction
B. frequency
C. rarefaction
D. wavelength
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Answer
The answer is B. If you were watching a
transverse wave on a rope, the frequency of the
wave would be the number of crests or troughs
that pass you each second.
Sound
Sound Waves
Waves
2
Making Sound Waves
• Vibrations transfer
energy to nearby air
particles, producing
sound waves in air.
• Every sound you
hear is caused by
something vibrating.
For example, when you talk, tissues in your
throat vibrate in different ways to form sounds.
Sound
Sound Waves
Waves
2
Sound Waves are
Compressional Waves
• Sound waves produced by a vibrating object
are compressional waves.
• A vibrating drum head
produces a sound wave.
• The drum head produces
a compression each time
it moves upward and a
rarefaction each time it
moves downward.
Sound
Sound Waves
Waves
2
Sound Waves are
Compressional Waves
• Sound waves
travel faster
through solids
and liquids.
Sound
Sound Waves
Waves
2
The Speed of Sound
• The speed of sound
through a material
increases as the
temperature of the
material increases.
• The effect of
temperature is
greatest in gases.
Sound
Sound Waves
Waves
2
The Loudness of Sound
• By interpreting the
reflected waves, the
animals can locate
and determine
properties of other
animals.
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Question 1
Every sound you hear is caused by something
that is _______.
A. compressing
B. loud
C. moving
D. vibrating
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Answer
The answer is D. The sound of your voice is
caused by vibrations in your vocal chords.
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Question 2
Sound waves travel
faster through
_______ than they
do through water.
A. gases
B. liquids
C. plasma
D. solids
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Answer
The answer is D. This
table shows that sound
waves travel faster
through solids than
they travel through
water.
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Question 3
Each increase of 10 dB in intensity multiplies
the energy of a sound wave by _______.
A. 10
B. 100
C. 1,000
D. 10,000
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Answer
The answer is A. Most people perceive this as
a doubling of the loudness of the sound.
Light
Light
3
Waves in Empty Space
• Light from the Moon has
traveled through space that
contains almost no matter.
• You can see light from the
moon, distant stars, and
galaxies because light is
an electromagnetic wave.
Light
Light
3
Waves in Empty Space
• Electromagnetic waves
are waves that can travel
through matter or through
empty space.
Light
Light
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The Speed of Light
Answer
Electromagnetic waves can travel through
empty space.
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Question 2
No material thing, including spaceships, can
move faster than _______.
Answer
The answer is the speed of light. Light speed is
the upper limit on travel through space.
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Question 3
Which contains a higher frequency?
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A. gamma rays
B. infrared waves
C. microwaves
D. radio waves
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Answer
The answer is A. As wavelength decreases,
frequency increases.
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