4. What is a wave?
Read intro page 201
*A wave is a disturbance that travels
through a medium from one location
to another.
*A wave is the motion of a
disturbance
Examples: Waves in water; Seismic
waves in the Earth
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5. 12.1 Waves Read page 201
If we poke a ball floating on
water, it will bob up and down
(harmonic motion).The
oscillating ball creates a wave
on the water surface.
— What is oscillation?
Oscillation is a system of
harmonic motion The first ball
can make a second ball that is
farther away oscillate. (move)
Explain the transfer of energy.
Water Demo
6. 12.1 Waves Read page 201
*Harmonic Motion: Motion that
repeats itself. Like a ball
bobbing up and down in the
water
*What is oscillation?
Oscillation is a system of
harmonic motion
Example: The first ball can
make a second ball that is
farther away oscillate. (move)
Water Demo
7. Read page 202
12.1 Evidence of waves
Anytime you see a vibration that moves
Anything that makes or responds to sound
Anything that makes or responds to light
Anythingthat transmits information through the air
(or space) without wires
— cell phones, radio, and television.
Anything that allows you to “see through” objects
— ultrasound, CAT scans, MRI scans, and X rays
8. 1. When you transmit information
without anything obviously moving,
you are using waves.
A. Yes
B. No
9. 2. How many different types of waves
are there?
2.0
0.1
10. There are Two Types of Waves:
1. *A transverse wave has its oscillations
perpendicular to the direction the wave
moves.
(In other words: the wave bobs up and down)
Read page 203
14. There are Two Types of Waves:
2. *A longitudinal wave has its
oscillations in the same direction as the
wave moves.
Read page 203
15. *Longitudinal Wave
The wave we see here is a longitudinal wave.
The medium particles vibrate parallel to the
motion of the pulse.
*This is the same type of wave that we use to
transfer sound.
Can you figure out how??
show tuning fork demo
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22. Read page 204
Anatomy of a Wave
Now we can begin to describe the
anatomy of our waves.
We will use a transverse wave to describe
this since it is easier to see the pieces.
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23. *Anatomy of a Wave
*In our wave here the dashed line represents the
equilibrium position.
Once the medium is disturbed, it moves away
from this position and then returns to it
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24. Anatomy of a Wave
crest
The points A and F are called the CRESTS
of the wave.
*The crest is the point where the wave
exhibits the maximum amount of positive or
upwards displacement. (the top of the
wavelength)
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25. Anatomy of a Wave
trough
The points D and I are called the
TROUGHS of the wave.
*The troughs are the points at the bottom
of wavelength)
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26. Anatomy of a Wave
Amplitude
*The distance between the dashed line and
point A is called the Amplitude of the wave.
This is the maximum displacement that the
wave moves away from its equilibrium.
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27. Anatomy of a Wave
wavelength
The distance between two consecutive similar
points (in this case two crests) is called the
wavelength.
*The wavelength is the length of the wave pulse.
Between what other points is can a wavelength be
measured?
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28. 4. There are two ways to
measure a wave: from crest to
crest
A. Trueor trough to trough.
B. False
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29. Wave frequency
We know that frequency measure how
often something happens over a certain
amount of time.
We can measure how many times a pulse
passes a fixed point over a given amount
of time, and this will give us the
frequency.
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30. Wave Frequency
* The frequency of a wave is a measure
of how often it goes up and down.
*Wave frequency is measured in hertz.
30
43. Your Turn:
Answer these questions with a partner:
1. Which of the following things must involve a wave? You
may pick more than one. Explain each of your choices.
a) A bulldozer is moving the dirt for a highway
b) A person is talking to someone on a cell phone
c) An earthquake in the Pacific Ocean causes a house to
shake in Texas
d) A car is going 70 miles per hour on a highway
e) Two people stop to listen to a jet passing overhead
f) A doctor takes an X ray to check for broken bones
2. Draw a Transverse Wave. Label the a wavelength,
amplitude, crest and trough.