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Sound
Book page 118 ndash 124
Syllabus 326 ndash 332
copycgrahamphysicscom 2016 17052016 Wiener Philharmonic
What is that sound
copycgrahamphysicscom 2016
Starter
bull Draw and label how sound waves are transmitted
copycgrahamphysicscom 2016
Aim bull Recall how sound waves are produced
bull Describe the characteristics of sound waves
bull Explain echoes
Key words
bull Pitch
bull Frequency
bull Echo
bull Audible range
copycgrahamphysicscom 2016
copycgrahamphysicscom 2016
The big picture
Have you ever wondered
Do stars make sound Sound of Stars
Sounds are made when particles vibrate
The longitudinal waves produced are detected as sound
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
What is that sound
copycgrahamphysicscom 2016
Starter
bull Draw and label how sound waves are transmitted
copycgrahamphysicscom 2016
Aim bull Recall how sound waves are produced
bull Describe the characteristics of sound waves
bull Explain echoes
Key words
bull Pitch
bull Frequency
bull Echo
bull Audible range
copycgrahamphysicscom 2016
copycgrahamphysicscom 2016
The big picture
Have you ever wondered
Do stars make sound Sound of Stars
Sounds are made when particles vibrate
The longitudinal waves produced are detected as sound
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Starter
bull Draw and label how sound waves are transmitted
copycgrahamphysicscom 2016
Aim bull Recall how sound waves are produced
bull Describe the characteristics of sound waves
bull Explain echoes
Key words
bull Pitch
bull Frequency
bull Echo
bull Audible range
copycgrahamphysicscom 2016
copycgrahamphysicscom 2016
The big picture
Have you ever wondered
Do stars make sound Sound of Stars
Sounds are made when particles vibrate
The longitudinal waves produced are detected as sound
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Aim bull Recall how sound waves are produced
bull Describe the characteristics of sound waves
bull Explain echoes
Key words
bull Pitch
bull Frequency
bull Echo
bull Audible range
copycgrahamphysicscom 2016
copycgrahamphysicscom 2016
The big picture
Have you ever wondered
Do stars make sound Sound of Stars
Sounds are made when particles vibrate
The longitudinal waves produced are detected as sound
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
copycgrahamphysicscom 2016
The big picture
Have you ever wondered
Do stars make sound Sound of Stars
Sounds are made when particles vibrate
The longitudinal waves produced are detected as sound
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Sounds are made when particles vibrate
The longitudinal waves produced are detected as sound
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
What vibrates so that the following make sounds
violin
strings drum
skin
voice box
loudspeaker
cone
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
How does sound reach your ear
When the drum skin is struck it vibrates which causes the air next to the drum to vibrate
The compression and rarefaction of air particles creates a sound wave
which travels through the air to your ear
longitudinal wave
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Sound waves (longitudinal)
Compression Rarefaction
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Remove the air from the bell jar
and what happens to the sound
The bell-jar experiment Place a ringing clock inside the bell jar and
what happens
The air allows the sound to travel and vibrate
With a vacuum inside the bell jar
the sound cannot be heard Why
vacuum
pump on
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
The speed of sound vs the speed of light
Sound travels at about 340 ms in air
Light travels at about 300 000 000 ms
This explains why we see lightning before we hear thunder
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
The sound wave is reflected back from the surface this is an echo
Echoes are reduced in cinemas by using soft surfaces like carpet and curtains which absorb sound waves
What happens when a sound wave meets a hard flat surface
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
1 Use a clapper board to make a sound
2 Measure the time taken between firing the pistol and
hearing the echo How far does the sound travel
START
150 m
Stand at least 100 m from a large flat wall with a stop watch
STOP
Experiment on echoes
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
How can you use this result to estimate the speed of sound
The sound of the wooden blocks takes 092 s
to travel a distance of 300 m
= 326 ms
distance
time speed =
= 300
092
Repeat the experiment several times to obtain an average
How does your calculation for the average speed of sound
compare with the real speed
Experiment on echoes
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Different speeds of sound
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Sound and states of matter
Sound waves travel by particles vibrating
bull The particles in a solid are closer together than
in a gas or a liquid
bull Vibrations are more easily passed from particle
to particle
bull Sound waves travel faster in a solid
solid gas liquid
Sound waves travel fastest through solids
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Which of these travel faster than the speed of sound in air
distance
(m)
time
(s)
speed
(ms)
small
aeroplane 600 5
jet fighter 900 2
cheetah 50 25
meteorite 10 000 035
120
450
28 571
20
The jet fighter and the meteorite break the sound
barrier What does this mean
Breaking the sound barrier
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
A sound wave can be displayed on an oscilloscope
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Oscilloscope ndash loudness
loud sound quiet sound Increasing the loudness increases the amplitude and the waves look taller
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Which is the loudest
Sound A is the loudest
Which trace represents the loudest sound
Sound A has the largest amplitude which
means the wave has more energy and so the
sound is louder
A B
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
low pitch sound high pitch sound
Oscilloscope - pitch
A higher pitch has a higher frequency so the waves look closer together
These sounds are the same volume because the amplitude is the same
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Which is the highest Which trace represents the sound with the highest pitch
Sound B is the highest pitched
Sound B has the shortest wavelength and the
most number of waves visible so it has the
highest frequency
B A
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Wave animation
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
How is an oscilloscope used to find the frequency of sound
bull How to find frequency from an oscilloscope
Example
An oscilloscope trace shows that the time period for a sound is 0005s What is the frequency of the wave
Solution
119891 =1
119879=
1
0005= 200119867119911
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Using an oscilloscope to find the speed of sound bull Set the signal generator to give frequency of 1 kHz bull Start with the microphones close together bull Observe how the traces compare on the screen bull Move one microphone away from the loudspeaker until it is
away one full wavelength from the first bull You know you have arrived on this point when the traces on
the screen are exactly above each other bull Measure the distance between the microphones this is the
wavelength bull Use the oscilloscope to get the frequency bull Use the equation 119907 = 119891λ to find the speed of sound
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
We know that light waves can be
Reflected
Refracted
Diffracted
bull Which of these apply to soundwaves
bull How are these phenomena called
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Sound waves
Refraction
bull Reflected sound is used to determine depth of ocean
bull Echo Locationmpg
Diffraction
bull Sound can bend around corners
bull Sound waves spread out around an obstacle or a small opening
bull Most noticeable when opening has same size as wavelength
copycgrahamphysicscom 2016
Reflection - echo
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
20 Hz to 20 000 Hz
Humans cannot hear sounds of every frequency
What is the hearing range of a healthy young person
The range of frequencies you can hear is called your
hearing range
What can you hear How Old Are Your Ears
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Ultrasound and infrasound
bull Ultrasound is sound that vibrates at frequencies greater than 20kHz
bull Infrasound is produced by sound waves vibrating below 20Hz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
X rays are more energetic and penetrating and are a lot more
dangerous they could cause damage to the growing baby
fetus at 10 weeks fetus at 20 weeks
Why is ultrasound for scanning a foetus instead of X rays which
would give a clearer picture
Ultrasound uses high frequency sound waves to produce
images of inside the body without opening up the body
Using ultrasound in medicine
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Plenary Sound multiple choice
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
Key words bull Pitch ndash is measured by frequency High pitch sounds have
high frequency
bull Frequency ndash how many waves cross a point in a unit of time
bull Echo ndash the reflection of sound waves The sound wave travels twice the distance until it is heard again
bull Audible range ndash the range of hearing of humans from 20Hz ndash 20kHz
copycgrahamphysicscom 2016
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