Characteristics of
Waves
Chapter 15, pages 472-492
1
What are Waves?



A wave is a disturbance that
transfers energy from place
to place
Waves travel through a
material called a medium.
Waves that require a
medium to travel through
are called mechanical
waves.
2
What are Waves?


Waves are created
when a source of
energy causes a
medium to vibrate.
A vibration is a
repeated back-andforth or up-and –down
motion.
3
Classification of Waves


Wave are classified
according to how they
move.
Types of waves:
1. Transverse
2. Longitudinal
3. Surface
4
Transverse Wave


In transverse waves, the
particles of the medium
move perpendicular in the
direction of the wave.
Parts of the transverse
wave:




Crest
Trough
Wavelength
Amplitude
5
Longitudinal Wave


In longitudinal waves,
the particles of the
wave move parallel to
direction of the wave
movement.
Parts of the wave:



Compressions
Rarefactions
Wavelength
6
Surface Wave

Surface waves occur at
the boundary between
two mediums and are a
combination of
transverse and
longitudinal waves.
7
A transverse wave…..
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Vibrates particles perpendicular
to the direction of wave
Vibrates particles parallel to the
direction of the wave
Vibrates both parallel and
perpendicular to the direction of
the wave
Vibrates particles in one direction
I don’t get it.
A.
17
18
19
20
8
Properties of Waves

The basic properties of
waves are amplitude,
wavelength, frequency,
and speed.
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Amplitude


Amplitude is the
maximum distance the
particles of the
medium carrying the
wave move away from
their rest position.
Measured from crest to
resting position.
10
Wavelength


Wavelength is the
distance between
corresponding parts of
a wave.
Wavelength is
measured from crest to
crest.
11
Frequency


Frequency of a wave is
the number of complete
waves that pass a
given point in a certain
amount of time.
Frequency is measured
in hertz.
12
Wave Speed

Wave speed is how far
the wave travels in one
unit of time, or distance
divided by time.
13
Mathematical Relationship

The speed,
wavelength, and
frequency of a wave
are related to each
other by a
mathematical formula:
Speed=wavelength x frequency
14
In the diagram, identify the wave
property “A”
A.
B.
C.
D.
Frequency
Amplitude
Wavelength
I don’t know
22
0
A.
1
B.
0
C.
D.
15
Interaction of Waves
When waves interact,
three things can
happen to the waves:

1.
2.
3.
Reflect
Refract
Diffract
16
Reflection



Reflection happens when
waves bounce off of a
barrier.
The angle of incidence is
the angle between the
incoming wave and the
imaginary perpendicular
line.
The angle of reflection is
the angle between the
reflected wave and the
imaginary perpendicular
line.
17
Law of Reflection

The angle of reflection
is equal to the angle of
incidence.
18
Refraction



Refraction occurs as
the wave go between
different mediums.
The speed of a wave
changes as the
medium changes.
The change in speed of
the wave causes the
waves to bend.
19
Diffraction


Diffraction is the
bending of waves as
the waves go through a
small opening or
around a corner.
As the wave goes
through the hole or
around the corner, it
spreads out and bends.
20
Interference



Interference occurs as two
or more waves interact.
Constructive interference
happens when waves meet
and the amplitude
increases.
Destructive interference
happens when waves meet
and the amplitude
decreases.
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Standing Waves


Standing waves form
as the original wave is
interfered with by the
reflected wave.
The standing wave has
a node and an
antinode.
22
Review Questions


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What do we call the transfer of energy from place to place?
(wave)
What do we call the material through which waves travel?
(medium)
When the medium _______________, a wave is created.
(vibrate)
How are waves classified?
(how they move)
23
Review Questions

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The highest part of a transverse wave is called the
_______________.
(crest)
The lowest part of a transverse wave is called the
_______________.
(trough)
What type of wave travels parallel to the direction of the wave
travel?
(longitudinal)
What type of wave travels perpendicular to the direction of the
wave travel?
(transverse)
24
Review Questions


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What type of waves is on top of a pond or lake?
(surface)
What property of a wave is the maximum distance that particles
of the medium move from resting position?
(amplitude)
What do we call the distance between two corresponding parts of
a wave?
(wavelength)
In what units is frequency measured?
(hertz)
25
Review Questions




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


What is the mathematical relationship between speed of a wave,
frequency and wavelength?
(speed = wavelength x frequency)
When a wave hits a barrier and bounces back, it is called
_______________.
(reflection)
When a wave bends because it changes speed as it travels
through different mediums, it is called _______________.
(refraction)
When a wave bends as it travels around the edge of a barrier it is
called _______________.
(diffraction)
26
Review Questions








The interaction between two waves is called
________________.
(interference)
Waves combine to make a wave of larger amplitude is called
______________.
(constructive interference)
Waves combine to make a wave of lower or no amplitude is
called _______________.
(destructive interference)
What type of wave are two waves that interfere with each other
as they pass each other?
(standing)
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Review Questions


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What occurs when the vibration matches the natural frequency of
the object?
(resonance)
What are the highest and lowest points called on a standing
wave?
(antinodes)
What are the points of zero amplitude called on a standing
wave?
(nodes)
What type of waves does an earthquake produce?
(seismic)
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Review Questions

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Longitudinal seismic waves are called _______________.
(primary)
Transverse seismic waves are called _______________.
(secondary)
Which type of seismic wave causes the most damage?
(surface)
Which seismic wave is the fastest?
(primary)
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Review Questions
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What type of waves requires a medium to pass through?
(mechanical)
What name is given to the waves produce by underwater
earthquakes?
(tsunamis)
What machine measures ground movement?
(seismograph)
What scale is used to measure the magnitude of seismic waves?
(Richter)
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Review Questions
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What are the areas of a longitudinal wave where the waves are
close together?
(compressions)
What are the areas of a longitudinal wave where the waves are
far apart?
(rarefactions)
What is the angle defined by an incoming wave and the
imaginary perpendicular line?
(angle of incidence)
What is the angle defined by a reflected wave and the imaginary
perpendicular line?
(angle of reflection)
31
Review Questions
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
What is the relationship between the angle of incidence and the
angle of reflection?
(they are equal to each other)
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