Ride the WaveUnderstanding different

types of wave

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What do you know about

waves? Write down everything you can

think of related to waves… impress me with your vast

knowledge.

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Waves

• I can identify, describe and model the basic parts of a wave (amplitude, wavelength, wave speed, frequency, different mediums that waves travel through). (11.5)

• I can give examples of waves transmitting energy through matter or empty space. (11.6)

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Good, good, good, good vibrations!

http://www.youtube.com/watch?v=QSLMWasU0rM&feature=kp

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• Waves are created when a source of energy (force) causes a __________.

• So what are vibrations?

• A vibration is a repeated ________ and _________ motion or ____ and _____ motion.

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Waves transfer energy not matter. The water waves below are carrying energy but are not moving. Waves

can only exist as they have energy to carry.

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How do we How do we classify classify

WAVES?WAVES?7

Waves can be Waves can be classified by classified by WHATWHAT they move through they move through or by or by HOW energy HOW energy

moves through moves through them.them.

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Classification Classification of WAVES by of WAVES by WHAT they WHAT they

move through move through 9

There are two There are two classifications classifications forfor

waveswaves based on what based on what theythey move throughmove through: : Mechanical WavesMechanical Waves

Electromagnetic WavesElectromagnetic Waves10

What are What are mechanicmechanical al WAVESWAVES??

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Mechanical wavesMechanical waves are are waveswaves that can that can ONLYONLY

movemove throughthrough a a mediummedium (through (through

mattermatter).).12

Mechanical wavesMechanical waves requirerequire thethe particlesparticles

ofof thethe mediummedium toto vibratevibrate in order for in order for

energyenergy toto bebe transferredtransferred..

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What are What are examples examples

mechanical mechanical WAVESWAVES??

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water waveswater waves earthquake/seismic earthquake/seismic

waveswaves sound wavessound waves

waves that travel down a waves that travel down a rope or springrope or spring

All of these All of these examplesexamples CANNOTCANNOT move through move through empty spaceempty space..

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A wave moving through a medium travels at a certain speed. This is

Wave Speed.

Wave speed is usually measured in meters/second, but may be measured using other distance units (such as centimeters per

second).16

What areWhat are electromagnetelectromagnet

ic ic WAVESWAVES??17

Electromagnetic wavesElectromagnetic waves areare waveswaves that can that can

travel through travel through mattermatter or or empty spaceempty space where where mattermatter isis not presentnot present..

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What isWhat is EMPTY EMPTY SPACESPACE??

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Empty spaceEmpty space is is space in which space in which NO NO MATTERMATTER is present. is present. Another name for Another name for this is this is a vacuuma vacuum..

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What are What are examples of examples of electromagnelectromagnetic WAVESetic WAVES??

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radio wavesradio wavesmicrowavesmicrowaves

infrared wavesinfrared wavesvisible lightvisible light

ultraviolet raysultraviolet raysX-raysX-rays

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I can examine how transverse and longitudinal waves are produced and transmitted. (Longitudinal waves- rarefaction and compression; Transverse wave- crest and trough). (11.5)

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Classification of Classification of WAVES WAVES byby HOWHOW energy moves energy moves through them through them

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There are two There are two classifications classifications for for waveswaves

based on how energy based on how energy moves through moves through them: them: Longitudinal WavesLongitudinal WavesTransverse WavesTransverse Waves

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What are What are longitudinalongitudinal WAVESl WAVES??

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Mechanical wavesMechanical waves in which the in which the particlesparticles of of mattermatter in the in the

mediummedium vibratevibrate byby pushing pushing togethertogether andand moving apartmoving apart parallelparallel to the to the directiondirection in in which the wave travelswhich the wave travels are are called called longitudinal waveslongitudinal waves..

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Compressional/ Longitudinal Wave

On a compressional wave the area squeezed together is called the compression. The areas spread out are called the rarefaction.

The wavelength is the distance from the center of one compression to the center of the next compression.

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http://www.lcse.umn.edu/specs/labs/glossary_items/rarefaction_spring.htmlhttp://www.lcse.umn.edu/specs/labs/glossary_items/rarefaction_spring.html

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The place on the The place on the wavewave that is that is pushed togetherpushed together

is called theis called the compression compression and the and the place that is place that is moving moving

apartapart is the is the rarefactionrarefaction..

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What are What are examples of examples of

compressionacompressional/ l/

longitudinal longitudinal waveswaves??

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sound wavessound wavessome waves in a springsome waves in a spring

some seismic waves some seismic waves (earthquake waves- (earthquake waves- primary waves, to be primary waves, to be

exact)exact)

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What is sound?

Sound is a compressional wave which travels through the air through a series of compressions and rarefactions.

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“Seeing Sound”

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Sound travels through different media.

We hear sound which usually travels through air. Sound travels through other media as well, such as water and various solids.

Sound travels different speeds in different media. Sound typically travels faster in a solid that a liquid and faster in a liquid than a gas.

The denser the medium, the faster sound will travel.

The higher the temperature, the faster the particles of the medium will move and the faster the particles will carry the sound. 35

What are What are transverse transverse

WAVESWAVES??36

Mechanical wavesMechanical waves in which in which the the particlesparticles ofof mattermatter in the in the mediummedium vibratevibrate by moving by moving

back and forthback and forth and and perpendicularperpendicular ((at right at right

anglesangles) to the ) to the direction the direction the wave travelswave travels are called are called

transverse wavestransverse waves..

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science.hq.nasa.gov/kids/imagers/ems/waves3.html science.hq.nasa.gov/kids/imagers/ems/waves3.html 38

The The highest pointhighest point of of a a transverse wavetransverse wave is the is the crestcrest and the and the

lowest pointlowest point is is called a called a troughtrough..

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What is wavelength?

Wavelength is a measure of distance, so the units for wavelength are always distance units, such as meter, centimeters, millimeters, etc.

What is wave frequency?

Frequency is the number of waves that pass through a point in one second. The unit for frequency is waves per second or Hertz (Hz). One Hz = One wave per second.

Wavelength and frequency are inversely related.

The smaller the wavelength, the more times it will pass through a point in one second. The larger the wavelength, the fewer times it will pass through a point in one second.

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The amplitude of a transverse wave is determined by the height of the crest or depth of the trough

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http://www.stmary.ws/highschool/physics/home/animations3/waves/Wave_Characteristics.html

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What are What are examples of examples of transverse transverse

waveswaves??43

Example of a transverse wave:

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strings on a musical strings on a musical instrument (not the sound)instrument (not the sound)

waves on a ropewaves on a ropesome waves in a springsome waves in a spring

some seismic waves some seismic waves (earthquake waves- (earthquake waves-

secondary waves, to be secondary waves, to be exact)exact)

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What are Seismic Waves?

An energy wave which vibrates through the earth’s crust as the crust bends or breaks. Seismic waves exist as both transverse and longitudinal waves. Some travel through the earth and some travel across the earth’s surface.

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Electromagnetic waves Electromagnetic waves areare transverse wavestransverse waves thatthat can can travel without a travel without a mediummedium

through through empty spaceempty space..Examples: Radio Waves,

Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma

Rays

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http://www.stmary.ws/highschool/physics/home/animations3/wavemotion.html

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Properties of LightProperties of LightLight is an example of a

transverse wave.

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Visible Light WavesWaves with a length of between 0.4 and 0.7 micrometers can be detected by the human eye. For these reason we call these waves visible light.

As you look around the room everything you see has these waves bouncing off of them. If they didn’t, you would not be able to see them. What your eyes pickup and turn into a picture in your brain, are these visible light waves

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Light travels VERY FAST – around 300,000 kilometres per second.

per second.

At this speed it can go around the world 8 times in one second.

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Light travels much faster than sound. For example:

1) Thunder and lightning start at the same time, but we will see the lightning first.

2) When a starting pistol is fired we see the smoke first and then hear the bang.

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We see things because they reflect light into our eyes:

Homework

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Shadows

Shadows are places where light is “blocked”:

Rays of light

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The colors of the rainbow:The colors of the rainbow:

RedOrangeYellowGreenBlue

IndigoViolet

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Seeing colorSeeing colorThe color an object appears depends on the

colors of light it reflects.

For example, a red book only reflects red light:

White

light

Only red light is

reflected

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A white hat would reflect all seven colors:

A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and

blue):

Purple light

White

light

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Using filtersUsing filtersFilters can be used to absorb or “block” out different

colors of light:

Red Filte

r

Magenta

Filter

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I can investigate wave interactions through textual analysis and lab activities, summarizing their causes and effects (diffraction, interference both constructive and destructive, reflection and refraction). (11.6)

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The Behavior of Waves

What is reflection?

When a wave bounces off an object and changes direction – this is reflection.

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ReflectionReflectionReflection from a mirror:

Incident ray

Normal

Reflected ray

Angle of incidence

Angle of reflection

Mirror 61

The Law of ReflectionThe Law of Reflection

Angle of incidence = Angle of Angle of incidence = Angle of reflectionreflection

In other words, light gets reflected from a surface at ____ _____ angle it hits.

The same !

!!

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What is sonar?

Sonar is a system that uses the reflection of underwater sound waves to detect objects. This has been used to find sunken ships and schools of fish.

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What is Refraction?

Refraction is the bending of a wave as it passes from one medium to another. A wave travels at different speeds in different things. When a wave traveling a certain speed moves into another medium, it will either increase in speed or decrease in speed, resulting in a change in direction.

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What is diffraction?

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

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Diffraction also occurs when passing through a small opening. They diffract and spread out as they pass through the hole.

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What is Wave Interference?Waves interfere in one of two ways: Constructive

Interference and Destructive Interference.

Constructive Destructive

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Extra Fun… Extra Fun…

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How is frequency related to pitch?

The pitch of a sound wave is directly related to frequency. A high-pitched sound has a high frequency (a screaming girl). A low-pitched sound has a low frequency (a fog-horn).

A healthy human ear can hear frequencies in the range of 20 Hz to 20,000 Hz. Humans cannot hear below 20 Hz. Sounds below this frequency are termed infrasonic.

Sounds above 20,000 Hz are termed ultrasonic. Some animals, such as dogs, can hear frequencies in this range in which humans cannot hear.

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Sound – The basics of frequency and pitch.

We hear things when they vibrate.

If something vibrates with a high frequency (vibrates very quickly) we say it has a high pitch.

If something vibrates with a low frequency (vibrates slowly) we say it has a low pitch. 75

Drawing sounds…

This sound wave has a _____ frequency:

This sound wave has a ___ _frequency:

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Drawing sounds…

This sound wave has a _____ amplitude (loud):

This sound wave has a _____ amplitude (quiet):

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http://www.stmary.ws/highschool/physics/home/animations3/waves/wave_measure.html

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Other sound effects…

Like light, sound can be…

1)Reflected – sound reflections are called ______.

2)Refracted – this is why you might sound strange if you try talking underwater

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Loudness in Decibels

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What is the Doppler Effect?

The Doppler Effect is the apparent change in frequency detected when the sound is moving relative to the hearer.

http://www.stmary.ws/highschool/physics/home/animations3/waves/DopplerEffectTrain.html

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Using Sound: What is Acoustics?

Acoustics is the study of sound and ways to optimize the hearing of sound inside various structures.

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What is echolocation?

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