Waves Chapter 10 Section 1 The Nature of Waves. Waves The Nature of Waves slides 1-20 The Nature of Waves slides 1-20 Wave Properties slides 21- 46 Wave

WavesWaves

Chapter 10 Section 1Chapter 10 Section 1

The Nature of WavesThe Nature of Waves

WavesWaves

The Nature of Waves slides 1-20The Nature of Waves slides 1-20 Wave Properties slides Wave Properties slides 21- 4621- 46 The Behavior of Waves slides The Behavior of Waves slides 46 -97 46 -97

WavesWaves

A A wavewave is a repeating disturbance or is a repeating disturbance or movement that transfers energy movement that transfers energy through it.through it.

WavesWaves

A A wavewave is a repeating disturbance or is a repeating disturbance or movement that transfers energy movement that transfers energy through it.through it.

Examples:Examples: MicrowavesMicrowaves Radio wavesRadio waves Sound wavesSound waves Ocean wavesOcean waves

Waves and EnergyWaves and Energy

A pebble falling into a pool causes a A pebble falling into a pool causes a disturbance which transfers energy disturbance which transfers energy to the water molecules nearby which to the water molecules nearby which in turn pass the energy along to in turn pass the energy along to molecules that are next to them. A molecules that are next to them. A wave is formed that carries the wave is formed that carries the energy along the surface of the energy along the surface of the water.water.

Do waves carry matter?Do waves carry matter?

A boat on a lake may move up and A boat on a lake may move up and down or even back and forth a little down or even back and forth a little with a wave but is not carried to a with a wave but is not carried to a different position.different position.

The wave ONLY carries energy The wave ONLY carries energy without moving matter.without moving matter.

How can you make a How can you make a wave?wave?

A wave will travel as long as there is A wave will travel as long as there is both energy & a medium to carry it.both energy & a medium to carry it.

How can you make a How can you make a wave?wave?

A wave will travel as long as there is A wave will travel as long as there is both energy & a medium to carry it.both energy & a medium to carry it.

Anything that moves up & down or Anything that moves up & down or back and forth is a vibrating back and forth is a vibrating movement.movement.

Vibrations cause all waves.Vibrations cause all waves.

Mechanical WavesMechanical Waves

A A mediummedium is the matter through is the matter through which a wave travels. It can be solid, which a wave travels. It can be solid, liquid, or gas or a combination.liquid, or gas or a combination.


A A mediummedium is the matter through is the matter through which a wave travels. It can be which a wave travels. It can be solid, liquid, or gas or a combination.solid, liquid, or gas or a combination.

Light and radio waves do not need a Light and radio waves do not need a medium & can travel through space.medium & can travel through space.


A A mediummedium is the matter through is the matter through which a wave travels. It can be solid, which a wave travels. It can be solid, liquid, or gas or a combination.liquid, or gas or a combination.

Light and radio waves do not need a Light and radio waves do not need a medium & can travel through space.medium & can travel through space.

Waves that can only travel through a Waves that can only travel through a medium are called medium are called mechanical waves.mechanical waves. TransverseTransverse CompressionalCompressional


Waves that can only travel through a Waves that can only travel through a medium are called medium are called mechanical waves.mechanical waves. Transverse- the matter in the medium Transverse- the matter in the medium

moves at a right angle to the direction moves at a right angle to the direction the wave travels; ex. Ocean wavethe wave travels; ex. Ocean wave

Compressional (longitudinal)- matter Compressional (longitudinal)- matter moves back and forth in the same moves back and forth in the same direction that the wave travels ex. springdirection that the wave travels ex. spring


Transverse Wave Compressional Waves

How do sound waves How do sound waves move?move?

Sounds waves are compressional Sounds waves are compressional waves which travel through air, waves which travel through air, water, and wood. When the sound water, and wood. When the sound wave reaches your ear, it causes wave reaches your ear, it causes your eardrum to vibrate, sending your eardrum to vibrate, sending signals to your brain which you signals to your brain which you understand as sound.understand as sound.

How do water waves How do water waves move?move?

Water waves are a Water waves are a combination of combination of transverse & transverse & compressional compressional waves. The water waves. The water moves up & down moves up & down & back & forth & back & forth ending up where it ending up where it began.began.

How do ocean waves How do ocean waves move?move?

Wind blowing across the ocean Wind blowing across the ocean surface causes most ocean waves to surface causes most ocean waves to form.form.

How do ocean waves How do ocean waves move?move?

Wind blowing across the ocean Wind blowing across the ocean surface causes most ocean waves to surface causes most ocean waves to form.form.

Size of the wave depends on:Size of the wave depends on: Speed of the windSpeed of the wind Length of time the wind blowsLength of time the wind blows How far it travels over the waterHow far it travels over the water

What are seismic waves?What are seismic waves?

Seismic waves are a combination of Seismic waves are a combination of transverse & compressional waves transverse & compressional waves that carry energy outward and cause that carry energy outward and cause an earthquake.an earthquake.


Transverse Waves Compressional waves

How they move

How they move

example

example


Transverse Waves Compressional waves

How they move

How they move

example

example

the matter in the the matter in the medium moves at a medium moves at a right angle to the right angle to the direction the wave direction the wave travelstravels

matter moves back and matter moves back and forth in the same forth in the same direction that the wave direction that the wave travelstravels

Ocean wavesSpring or slinky, sounds

Wave PropertiesWave Properties


Parts of a Wave

Crest Trough Rarefaction

Parts of a Wave

Crest – high point of a transverse wave Trough – low point of a transverse wave Rarefaction – area where the medium is

more spread out

Compressional WaveCompressional Wave

Rarefaction – area where the medium is more spread out

Parts of a Wave

Wavelength- distance b/w one point on a wave and the nearest point just like it.

Human HearingHuman Hearing

Only hear sounds that have Only hear sounds that have wavelengths with measures between wavelengths with measures between a few cm and about 15 m.a few cm and about 15 m.

Frequency and PeriodFrequency and Period

Frequency- Frequency- number of wavelengths number of wavelengths that pass by a point each second, that pass by a point each second, expressed in Hz (hertz) ex. Choosing expressed in Hz (hertz) ex. Choosing radio station.radio station.

Frequency and PeriodFrequency and Period

Frequency- Frequency- number of wavelengths number of wavelengths that pass by a point each second, that pass by a point each second, expressed in Hz (hertz) ex. Choosing expressed in Hz (hertz) ex. Choosing radio station.radio station.

Period- Period- amount of time it takes one amount of time it takes one wavelength to pass a point, wavelength to pass a point, measured in seconds.measured in seconds.

How are frequency & How are frequency & wavelength related?wavelength related?

As the frequency of waves increases, As the frequency of waves increases, their wavelength decreasestheir wavelength decreases

Wave SpeedWave Speed

Light waves travel through gases Light waves travel through gases much faster than sound waves.much faster than sound waves.



The speed of a wave depends on the The speed of a wave depends on the medium it is traveling through.medium it is traveling through.




Sound waves (compression) usually Sound waves (compression) usually travel faster than light waves travel faster than light waves through liquids and solids.through liquids and solids.


Light waves travel through gases much Light waves travel through gases much faster than sound waves.faster than sound waves.


Sound waves (compression) usually travel Sound waves (compression) usually travel faster than light waves through liquids faster than light waves through liquids and solids.and solids.

Sound waves usually travel faster in a Sound waves usually travel faster in a material if the temperature of the material if the temperature of the material is increased.material is increased.

How do you calculate wave How do you calculate wave speed?speed?

Calculate speed by multiplying its Calculate speed by multiplying its frequency times its wavelength. The frequency times its wavelength. The Greek letter lambda (Greek letter lambda (λλ) represents ) represents wavelength, f is frequency, and v wavelength, f is frequency, and v represents the speed of the wave. represents the speed of the wave.



Speed (m/s) = frequency (Hz) X Speed (m/s) = frequency (Hz) X wavelength ( in m) or wavelength ( in m) or v = f v = f λλ



Speed (m/s) = frequency (Hz) X Speed (m/s) = frequency (Hz) X wavelength ( in m) or wavelength ( in m) or v = f v = f λλ

What is the speed of a sound wave What is the speed of a sound wave that has a frequency of 150 Hz and a that has a frequency of 150 Hz and a wavelength of 0.00002 mm? Show wavelength of 0.00002 mm? Show your work.your work.


What is the speed of a sound What is the speed of a sound wave that has a frequency of 150 wave that has a frequency of 150 Hz and a wavelength of 0.00002 Hz and a wavelength of 0.00002 mm? Show your work.mm? Show your work.

F = 150 Hz F = 150 Hz λλ = 0.00002 mm = 0.00002 mm



F = 150 Hz F = 150 Hz λλ = 0.00002 mm = 0.00002 mm V = f V = f λλ = =



F = 150 Hz F = 150 Hz λλ = 0.00002 mm = 0.00002 mm V = f V = f λλ = 150 Hz X 0.00002 mm = 150 Hz X 0.00002 mm



F = 150 Hz F = 150 Hz λλ = 0.00002 mm = 0.00002 mm V = f V = f λλ = 150 Hz X 0.00002 mm = 150 Hz X 0.00002 mm V = .003 mm/sV = .003 mm/s

Amplitude and EnergyAmplitude and Energy

Amplitude Amplitude – measure of the energy – measure of the energy that a wave carries. The greater the that a wave carries. The greater the amplitude, the more energy the amplitude, the more energy the wave carries.wave carries.


Amplitude Amplitude – measure of the energy – measure of the energy that a wave carries. The greater the that a wave carries. The greater the amplitude, the more energy the amplitude, the more energy the wave carries.wave carries.

Compressional waves Compressional waves amplitude amplitude depends on how tightly the medium depends on how tightly the medium is pushed together at the is pushed together at the compressions.compressions.


Amplitude Amplitude – measure of the energy – measure of the energy that a wave carries. The greater the that a wave carries. The greater the amplitude, the more energy the wave amplitude, the more energy the wave carries.carries.

Compressional waves Compressional waves amplitude amplitude depends on how tightly the medium is depends on how tightly the medium is pushed together at the compressions.pushed together at the compressions.

Transverse wavesTransverse waves amplitude = amplitude = distance from the crest or trough of distance from the crest or trough of the wave to the rest positionthe wave to the rest position

Properties of waves

Properties of waves

Wavelength

Frequency

Period

Wave speed

Amplitude

Energy

The Behavior of The Behavior of WavesWaves


ReflectionReflection

Wave reflectionWave reflection happens when a happens when a wave wave strikesstrikes an object or surface an object or surface and bouncesand bounces off of it. off of it.

ReflectionReflection

Wave Wave reflectionreflection happens when a happens when a wave strikeswave strikes an object or surface an object or surface and bouncesand bounces off of it. off of it.

AllAll types of types of waveswaves, including sound, , including sound, water, and light waves, water, and light waves, can be can be reflectedreflected..

How do light waves How do light waves reflect?reflect?

Light waves strike Light waves strike canal houses in canal houses in Amsterdam; then Amsterdam; then the reflected the reflected waves strike water waves strike water in the canal and in the canal and bounce off creating bounce off creating this image this image captured by the captured by the camera.camera.

Law of ReflectionLaw of Reflection

The light beam The light beam striking the mirror striking the mirror is called the is called the incident beamincident beam..


The light beam The light beam striking the mirror striking the mirror is called the is called the incident beam.incident beam.

The line that is at a The line that is at a right angle to the right angle to the mirrormirror is called the is called the normal.normal.

Normal

Law of ReflectionLaw of Reflection The light beam The light beam

striking the mirror is striking the mirror is called the called the incident incident beam.beam.

The line that is at a The line that is at a right angle to the right angle to the mirror is called the mirror is called the normal.normal.

The light beam that The light beam that bounces off the mirrorbounces off the mirror is called the is called the reflected reflected beambeam..

Normal


The angle made by The angle made by the incidence the incidence beam and the beam and the normal is the normal is the angle angle of incidence.of incidence.

Normal

Angle of incidence


The angle made by The angle made by the incidence the incidence beam and the beam and the normal is the normal is the angle angle of incidence.of incidence.

The angle made by The angle made by the reflected beam the reflected beam and the normal is and the normal is the the angle of angle of reflection.reflection.

Normal

Angle of incidence

Angle of reflection


The law of The law of reflection says that reflection says that the the angle of angle of incidence incidence is equal is equal toto the the angle of angle of reflectionreflection.. Norma

l

Angle of incidence

Angle of reflection

What are echoes?What are echoes?

Echoes are Echoes are reflected sound reflected sound waveswaves..

What are echoes?What are echoes?

Echoes are Echoes are reflected sound reflected sound waves.waves.

If a sound is not If a sound is not absorbed or absorbed or transmittedtransmitted when when it strikes a surface, it strikes a surface, it will be reflectedit will be reflected..

What are echoes?What are echoes? Echoes are reflected Echoes are reflected

sound waves.sound waves. If a sound is not If a sound is not

absorbed or absorbed or transmitted when it transmitted when it strikes a surface, it strikes a surface, it will be reflected.will be reflected.

The law for reflection The law for reflection is the same as that for is the same as that for light, i.e. light, i.e. the angle of the angle of incidence of a sound incidence of a sound wave equals the angle wave equals the angle of reflectionof reflection..

RefractionRefraction

Can you recall Can you recall seeing an object in seeing an object in water that appears water that appears to be broken?to be broken?



A A waves speed waves speed depends on the depends on the medium it is passing medium it is passing throughthrough; changing ; changing mediums may mediums may change speeds of the change speeds of the wave.wave.



A waves speed A waves speed depends on the depends on the medium it is passing medium it is passing through; changing through; changing mediums may mediums may change speeds of the change speeds of the wave.wave.

Refraction is the bending of Refraction is the bending of a wave caused by a change a wave caused by a change in its speed as it moves from in its speed as it moves from one medium to another.one medium to another.


Two things happenTwo things happen to the light waves to the light waves as they move from as they move from the air to the water the air to the water in the glass.in the glass. Change speedChange speed Change directionChange direction


As the light wave As the light wave slows downslows down, it , it bends towardbends toward the normal the normal..

Refraction/ReflectionRefraction/Reflection

As the light wave As the light wave slows downslows down, it , it bends bends towardtoward the normal. the normal.

As the light wave As the light wave speeds upspeeds up, it , it bends awaybends away from the normal.from the normal.

DiffractionDiffraction

DiffractionDiffraction takes takes place when an place when an object causes a object causes a wave to change wave to change directiondirection and bend and bend around it.around it.

DiffractionDiffraction

Diffraction takes Diffraction takes place when an place when an object causes a object causes a wave to change wave to change direction and bend direction and bend around it.around it.

Example: hearing Example: hearing sound coming from sound coming from another room.another room.

DiffractionDiffraction Diffraction takes place Diffraction takes place

when an object causes when an object causes a wave to change a wave to change direction and bend direction and bend around it.around it.

Example: hearing Example: hearing sound coming from sound coming from another room.another room.

Light waves do not Light waves do not refract as much as refract as much as sound waves though sound waves though they do bend around they do bend around edgesedges..

When do water waves When do water waves diffract?diffract?

Ocean waves diffract when they Ocean waves diffract when they strike an island. They change strike an island. They change direction and bend around the direction and bend around the island.island.

When do water waves When do water waves diffract?diffract?

Ocean wavesOcean waves diffract when they strike an island. diffract when they strike an island. They They change direction and bend around the change direction and bend around the islandisland..

Waves diffract when they pass through a narrow Waves diffract when they pass through a narrow opening spreading out afterwards, bending opening spreading out afterwards, bending around the corners of the opening.around the corners of the opening.

How much will a wave How much will a wave bend?bend?

Compare the size of the object to the Compare the size of the object to the wavelength:wavelength:


Compare the size of the object to the Compare the size of the object to the wavelength:wavelength: Smaller objectSmaller object, waves bend around it , waves bend around it

making making narrow shadownarrow shadow Object Object largerlarger than the wavelength, than the wavelength,

creates creates wider shadowwider shadow because the light because the light waves can’t bend as easily.waves can’t bend as easily.


Compare the size of the object to the Compare the size of the object to the wavelength:wavelength: Smaller object, waves bend around it Smaller object, waves bend around it

making narrow shadowmaking narrow shadow Object larger than the wavelength, Object larger than the wavelength,

creates wider shadow because the light creates wider shadow because the light waves can’t bend as easily.waves can’t bend as easily.

This is the shadow of a razor blade.This is the shadow of a razor blade.

How do sound waves bend How do sound waves bend around corners?around corners?

Wavelengths of sound are about the Wavelengths of sound are about the same size as the door opening so same size as the door opening so they diffract and spread into the they diffract and spread into the hallway.hallway.

How do sound waves bend How do sound waves bend around corners?around corners?

Wavelengths of sound are about the Wavelengths of sound are about the same size as the door opening so same size as the door opening so they diffract and spread into the they diffract and spread into the hallway.hallway.

This is different than from This is different than from light light waveswaves which have a which have a shorter shorter wavelengthwavelength than sound waves, thus than sound waves, thus light waves are not diffracted around light waves are not diffracted around the door as much as sound waves.the door as much as sound waves.

How do radio waves How do radio waves differ?differ?

AM (AM (amplitude modulatedamplitude modulated) radio waves ) radio waves have longer wavelengths than FM have longer wavelengths than FM ((frequency modulatedfrequency modulated) radio waves.) radio waves.

How do radio waves How do radio waves differ?differ?

AM (amplitude modulated) radio waves have longer AM (amplitude modulated) radio waves have longer wavelengths than FM (frequency modulated) radio wavelengths than FM (frequency modulated) radio waves.waves.

This means that AM waves can diffract around objects This means that AM waves can diffract around objects like buildings and mountains much more than FM radio like buildings and mountains much more than FM radio waves.waves.

InterferenceInterference

Interference Interference is the point where two is the point where two waves meet each other and overlap waves meet each other and overlap to form a new wave. to form a new wave.



The new wave lasts only as long as The new wave lasts only as long as the two waves continue to overlap.the two waves continue to overlap.



The new wave lasts only as long as The new wave lasts only as long as the two waves continue to overlap.the two waves continue to overlap.

There are There are two kindstwo kinds of interference: of interference: ConstructiveConstructive DestructiveDestructive


Interference Interference is the point where two is the point where two waves meet each other and overlap to waves meet each other and overlap to form a new wave. form a new wave.

The new wave lasts only as long as the The new wave lasts only as long as the two waves continue to overlap.two waves continue to overlap.

There are two kinds of interference:There are two kinds of interference: ConstructiveConstructive- waves meet and - waves meet and add togetheradd together DestructiveDestructive- waves overlap and - waves overlap and subtract subtract

from each other.from each other.

Constructive Constructive InterferenceInterference


The amplitudes The amplitudes add together to add together to make a make a larger larger wave with a higher wave with a higher crestcrest and a lower and a lower trough.trough.


The amplitudes add The amplitudes add together to make a together to make a larger wave with a larger wave with a higher crest and a higher crest and a lower trough.lower trough.

The The amplitudeamplitude of of the new wave is the new wave is the the sum of the sum of the amplitudes of the amplitudes of the other two waves.other two waves.

Destructive InterferenceDestructive Interference


The The amplitudes amplitudes combinecombine together together to make a to make a smaller smaller wave with a lower wave with a lower crestcrest and a higher and a higher trough.trough.


The amplitudes The amplitudes combine together to combine together to make a smaller wave make a smaller wave with a lower crest with a lower crest and a higher trough.and a higher trough.

The amplitudes The amplitudes cancel each other cancel each other out in both out in both transverse & transverse & compressionalcompressional waves.waves.

Standing WavesStanding Waves

A A standing wave is a wave pattern that standing wave is a wave pattern that forms when two equal-sized waves travel forms when two equal-sized waves travel in opposite directions and continuously in opposite directions and continuously interfereinterfere with each other. with each other.

Nodes where two waves cancel each otherNodes where two waves cancel each other

What are some examples of What are some examples of standing waves?standing waves?

Musical instruments:Musical instruments: Violin- bow creates standing waves in the stringsViolin- bow creates standing waves in the strings Flute creates standing waves in a column of airFlute creates standing waves in a column of air Drums vibrate to make standing wavesDrums vibrate to make standing waves

ResonanceResonance

All objects have their own natural All objects have their own natural frequencies of vibration.frequencies of vibration.

ResonanceResonance


Frequencies depend on the size and Frequencies depend on the size and shape of the object and what it is shape of the object and what it is made of.made of.

ResonanceResonance


Frequencies depend on the size and Frequencies depend on the size and shape of the object and what it is shape of the object and what it is made of.made of.

ResonanceResonance is when an object is when an object vibrates by absorbing energy from vibrates by absorbing energy from another object that is vibrating at its another object that is vibrating at its natural frequency.natural frequency.

ResonanceResonance Resonance can Resonance can

cause an object to cause an object to absorb so much absorb so much energy that it energy that it vibrates too much vibrates too much and breaks apartand breaks apart..

ResonanceResonance Resonance can cause an Resonance can cause an

object to absorb so object to absorb so much energy that it much energy that it vibrates too much and vibrates too much and breaks apart.breaks apart.

These are pictures of These are pictures of the the Tacoma Narrows Tacoma Narrows Bridge collapseBridge collapse on Nov. on Nov. 7, 1940, that was 7, 1940, that was caused by 42 mph winds caused by 42 mph winds creating a resonant creating a resonant response (28 ft waves) response (28 ft waves) by the bridge which was by the bridge which was over 1 mi long.over 1 mi long.

Skill Builder Concept Skill Builder Concept MapMap

Show the series of events that occur Show the series of events that occur to produce sound. Use to produce sound. Use rarefaction, rarefaction, vibration & compression.vibration & compression.



Vibration of matter



Vibration of matter

Compression of the medium



Vibration of matter

Compression of the medium

Rarefaction of the medium

Repeats as the sound wave travels through the medium

http://www.archive.org/http://www.archive.org/details/Pa2096Tacomadetails/Pa2096Tacoma

Documents

Waves Chapter 10 Section 1 The Nature of Waves. Waves The Nature of Waves slides 1-20 The Nature of Waves slides 1-20 Wave Properties slides 21- 46 Wave