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## Waves

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Title: Waves

1
Waves
• Chapter 14

2
Wave at the Shoe
3
Types of Waves
• A wave is a disturbance that carries energy
through matter or space.
• The medium is the matter through which a wave
travels.
• Waves that require medium are called mechanical
waves.

4
What is the wave called when it requires a medium?
1. mechanical
2. longitudinal
3. surface
4. transverse

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
5
Transverse waves
• Transverse waves are waves which the motion of
the particles is perpendicular to the motion of
the wave.
• The top of the wave is called the crest.
• The bottom of the wave is called the trough.
• The distance between the crest on one wave to the
crest on the next is called the wavelength.

6
Longitudinal wave
• Longitudinal waves are waves where the particles
in the medium vibrate parallel to the direction
of the wave motion.
• Compressions are the parts of the wave where the
medium is compressed.
• Rarefactions are parts of the wave where the
medium is spread apart.
• The distance between compressions is the
wavelength.

7
Surface waves
• Surface waves occur at the boundary between two
mediums.
• The particles move both perpendicularly and
parallel.

8
Which type of wave motion of the particles is
perpendicular to the motion of the wave?
1. longitudinal.
2. seismic.
3. surface.
4. transverse.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
9
Wave Properties(continued)
• Wavelength is the distance from one crest to the
crest of the next wave.
• Period is the time required for one full
wavelength of a wave to pass a certain point.
• Frequency of a wave is the number of full
wavelengths that pass a point in a given time
interval.

10
Wave Properties
• Transverse waves have the shape of a sine curve.
• Highest point of a transverse wave is a crest.
• Lowest point of a transverse wave is a trough.
• Amplitude is the greatest distance that particles
are displaced from their normal resting position.

11
In which type of a wave does the particles travel
perpendicular to the direction of the wave?
1. longitudinal
2. transverse
3. surface
4. none of the above

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
12
What is the top part of a wave called?
1. amplitude
2. compression
3. crest
4. trough

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
13
What do we call is the distance between two crest
on a transverse wave?
1. amplitude
2. frequency
3. period
4. wavelength

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
14
Frequency-Period Equation
• Frequency1/period
• F1/T
• Frequency is measured in a unit called a hertz.

15
Wave Speed
• wave speedfrequency x wavelength
• v f x ?

16
What unit is frequency measured?
1. joules
2. hertz
3. meters
4. newtons

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
17
Doppler Effect
• The Doppler Effect is the changed in the observed
frequency of a wave resulting from the motion of
the source or observer.
• As the source is approaching the observer, the
wavelength decreases and the pitch increases.
• As the source is going away from the observer,
the wavelength increases and the pitch decreases.

18
Doppler Effect
19
As a fire truck approaches you, what happens to
the sound?
1. pitch increases.
2. wavelength decreases.
3. sound gets louder.
4. all the above.

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21 22 23 24 25 26 27 28 29
20
Reflection
• Reflection is the bouncing back of a wave when it
meets a surface or boundary.

21
Diffraction
• Diffraction is when a wave bends around an object
or opening.

22
Refraction
• Refraction is the bending of a wave as it passes
from one medium to another medium.

23
A transverse wave..
1. Vibrates particles perpendicular to the direction
of wave
2. Vibrates particles parallel to the direction of
the wave
3. Vibrates both parallel and perpendicular to the
direction of the wave
4. Vibrates particles in one direction
5. I dont get it.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
24
In the diagram, identify the wave property A
1. Frequency
2. Amplitude
3. Wavelength
4. I dont know

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
25
What type of a wave interaction involves a wave
bending as it passes from one medium into another?
1. diffraction
2. reflection
3. refraction
4. I dont know

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29
26
Wave Interference
• Wave interference is when several waves are in
the same location and the waves combine to
produce a single, new wave that is different from
the original waves.

27
Constructive Interference
• The result of two individual waves coming
together to produce a wave of greater amplitude
is called constructive interference.

28
Destructive Interference
• The result of two individual waves coming
together to produce a wave of lesser amplitude
than the larger of the original waves is called
destructive interference.

29
Interference
• As two wave sources combine, the waves pattern
changes.

30
Beats
• Interference of sound waves produces beats.
• The beat frequency refers to the rate at which
the volume is heard to be oscillating from high
to low volume.

31
Standing Waves
• Standing wave is when the interference of the
original wave with the reflected wave causes the
medium to vibrate in a stationary pattern.

32
Standing Wave
• Nodes are the areas of a standing wave where
there are no vibrations.
• Antinodes are areas of a standing wave where
there is maximum vibration.

33
Longitudinal Wave
34
Transverse
35
Water Wave
36
Rayleigh Surface Wave
37
Review Questions
• Name the three types of waves.
• transverse, longitudinal surface
• Which type of wave has the particles moving
perpendicular to the motion of the wave?
• transverse
• Which type of wave has the particles moving
parallel to the motion of the wave?
• longitudinal

38
Review Questions
• Which three things can a wave do when it meets a
barrier?
• reflect, diffract or refract
• When the crest from one wave meets the crest of
another wave, what happens?
• constructive interference
• What do you call the top of a transverse wave?
• crest

39
Review Questions
• On a longitudinal wave, what do you call the part
of the wave that is spread out?
• rarefaction
• What is it called when the sound approaching you
gets louder and fades as it is going away from
you?
• Doppler Effect

40
Review Questions
• What happens when the crest of one wave meets the
trough of another wave?
• destructive interference
• What type of interaction occurs when a wave
strikes a barrier and bounces back?
• reflection

41
Review Questions
• What is the relationship between wave speed,
frequency wavelength?
• Wave speedfrequency x wavelength
• What do we call the interference of waves of
slightly different frequencies traveling in the
same direction?
• beat

42
Review Questions
• What is the bottom part of a transverse wave
called?
• trough
• What is the part of the longitudinal wave where
the wave is pressed closely together?
• compressions
• What is the interaction of a wave called where
the wave changes speed as it passes from one
medium to another and bends?
• refraction

43
Review Questions
• What is the distance between two crests on a
transverse wave called?
• wavelength
• What is the distance between a crest and the
resting position called?
• amplitude
• What do we call the number of waves that pass a
given point in a given amount of time?
• frequency

44
Review Questions
• What do we call the time it takes for one wave to
move past a given point?
• period
• What happens to the frequency of a wave as the
wavelength gets longer?
• lowers
• In which metric units do we measure frequency?
• hertz

45
Review Questions
• What is the material called that waves move
through?
• medium
• What type of wave needs a medium to move?
• mechanical
• What do we call a disturbance that transfers
energy?
• wave

46
Review Questions
• What type of wave is light?
• transverse
• What type of wave is sound?
• longitudinal
• What type of wave is produced when a wave is
interfered with by its reflected wave?
• Standing wave

47
Review Questions
• What is the part of a standing wave called where
there are no vibrations?
• nodes
• How does the medium affect the wave speed?
• the closer the particles, the faster the wave
speed
• Where do surface waves occur?
• boundary between two mediums

48
Internet Cites
• http//id.mind.net/zona/mstm/physics/waves/interf
erence/waveInterference2/WaveInterference2.html
• http//id.mind.net/zona/mstm/physics/waves/interf
erence/waveInterference1/WaveInterference1.html
• http//id.mind.net/zona/mstm/physics/waves/partsO
fAWave/waveParts.htm
• http//micro.magnet.fsu.edu/primer/java/wavebasics
/index.html
• http//www.bbc.co.uk/schools/gcsebitesize/physics/
waves/an_introduction_to_wavesrev4.shtml