What’s the deal What’s the deal with WAVE with WAVE

classification?classification?red wordsred words= vocabulary= vocabulary

How are How are WAVES WAVES

classifiedclassified??

WavesWaves can be classified can be classified by by WHATWHAT they move they move through or by through or by HOWHOW

energy moves through energy moves through them.them.

Wave SpeedWave Speed The The speed of a wavespeed of a wave depends on the depends on the

properties of the properties of the mediummedium it is it is traveling throughtraveling through In general sound waves travel the In general sound waves travel the

fastest through solids then liquids then fastest through solids then liquids then gasesgases

Light waves travel the fastest in empty Light waves travel the fastest in empty space and slowest through solidsspace and slowest through solids

Sound waves travel faster through Sound waves travel faster through warmer mediumswarmer mediums

The speed of waves The speed of a water wave is how fast

the wave spreads, NOT how fast the water surface moves up and down or how fast the dropped ball moves in the water.

How do we measure the wave speed?

Classification Classification ofof WAVES WAVES by by WHATWHAT they they

move throughmove through

What’s the deal with WAVE What’s the deal with WAVE classification?classification?

There are two classifications There are two classifications for waves based on what for waves based on what

they move through:they move through: •Mechanical WavesMechanical Waves

•Electromagnetic WavesElectromagnetic Waves

red wordsred words= vocabulary= vocabulary

What areWhat are mechanicamechanical WAVESl WAVES??

Mechanical wavesMechanical waves are are waves that can waves that can ONLYONLY

movemove through a through a medium (through medium (through

matter).matter).

Mechanical wavesMechanical waves require the particles of require the particles of the medium to vibrate the medium to vibrate in order for energy to in order for energy to

be transferred.be transferred.

What are What are examplesexamples

mechanical mechanical WAVESWAVES??

•water waveswater waves•earthquake/seismic wavesearthquake/seismic waves

•sound wavessound waves•waves that travel down a waves that travel down a

rope or springrope or spring

All of these examples All of these examples CANNOTCANNOT move through empty space.move through empty space.

What isWhat is EMPTY EMPTY SPACESPACE??

Empty spaceEmpty space is space is space in which in which NO MATTERNO MATTER is present. Another is present. Another name for this is a name for this is a

vacuumvacuum..

What areWhat are electromagnetelectromagnet

ic ic WAVESWAVES??

Electromagnetic wavesElectromagnetic waves are waves that can are waves that can

travel through matter travel through matter or empty space where or empty space where matter is not present.matter is not present.

What are What are examples ofexamples of

electromagnetielectromagnetic WAVESc WAVES??

•radio wavesradio waves•microwavesmicrowaves

•infrared wavesinfrared waves•visible lightvisible light

•ultraviolet raysultraviolet rays•X-raysX-rays

Classification of Classification of WAVESWAVES by HOW by HOW energy moves energy moves through themthrough them

There are two classifications There are two classifications for waves based on how for waves based on how

energy moves through them:energy moves through them: •Compressional/Longitudinal Compressional/Longitudinal

WavesWaves•Transverse WavesTransverse Waves

Seismic WavesSeismic Waves

Seismic wavesSeismic waves – combination of – combination of transverse and compressional waves transverse and compressional waves which carry energy along and through which carry energy along and through EarthEarth

What areWhat are compressional/ compressional/

longitudinal longitudinal WAVESWAVES??

Mechanical waves in which the Mechanical waves in which the particles of matter in the particles of matter in the

medium vibrate by pushing medium vibrate by pushing together and moving apart together and moving apart

parallelparallel to the direction in which to the direction in which the wave travels are calledthe wave travels are called compressional/longitudinal compressional/longitudinal

waveswaves..

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

The place on the wave The place on the wave 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..

What are examples What are examples ofof compressional/ compressional/

longitudinal longitudinal waveswaves??

•sound wavessound waves•some waves in a springsome waves in a spring

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

primary waves, to be exact)primary waves, to be exact)

What areWhat are transverse transverse WAVESWAVES??

Transverse wavesTransverse waves – matter moves in the – matter moves in the medium back and forth at right angles to medium back and forth at right angles to the direction that the wave is travelingthe direction that the wave is traveling Light waves & water wavesLight waves & water waves

Transverse WavesTransverse Waves

Mechanical waves in which the Mechanical waves in which the particles of matter in the particles of matter in the

medium vibrate by moving back medium vibrate by moving back and forth and perpendicular (at and forth and perpendicular (at right angles) to the direction the right angles) to the direction the

wave travels are calledwave travels are called transverse wavestransverse waves..

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

The highest point of a The highest point of a transverse wave is the transverse wave is the crestcrest and the lowest and the lowest

point is called a point is called a trough.trough.

What are What are examples ofexamples of transverse transverse

waveswaves??

•strings on a musical strings on a musical instrumentinstrument

•waves on a ropewaves on a rope•some 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)

Electromagnetic wavesElectromagnetic waves are transverse waves are transverse waves

that can travel without a that can travel without a medium through empty medium through empty

space.space.

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The Parts of a WaveThe Parts of a Wave

CrestCrest – the highest points of a wave – the highest points of a wave TroughTrough – the lowest points of a wave – the lowest points of a wave

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Radio WavesRadio stations transmit signals by changing a radio wave’s amplitude or frequency. What is the wave property that is constant?

Wireless Communication

WavelengthWavelength

WavelengthWavelength – the distance between one – the distance between one point on a wave and the nearest point just point on a wave and the nearest point just like itlike it

FrequencyFrequency andand PeriodPeriod

FrequencyFrequency – the number of waves that pass a – the number of waves that pass a given point each secondgiven point each secondØ Measured in Hertz = 1/sec Measured in Hertz = 1/sec Ø PeriodPeriod: The amount of time it takes one : The amount of time it takes one

wavelength to pass a pointwavelength to pass a point

FrequencyFrequency andand WavelengthWavelength

Frequency Frequency andand wavelengthwavelength are are inversely relatedinversely related Long wavelength Long wavelength

= Low frequency= Low frequency Short wavelength Short wavelength

= High Frequency= High Frequency

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Waves of the Electromagnetic Spectrum

The Electromagnetic SpectrumThe electromagnetic spectrum can be broken up into different categories. Use the word bank to complete the boxes in the diagram.

Four wave interactions

When a wave When a wave encounters a surface, encounters a surface, four interactions can four interactions can occur:occur:

reflection,reflection,

refraction, refraction,

diffraction, or diffraction, or

absorption.absorption.

Wave interactions

DiffractionDiffraction usually usually changes changes the the direction and shapedirection and shape of the wave. of the wave.

When a plane wave When a plane wave passes through a passes through a small hole small hole diffraction turns it diffraction turns it into a circular into a circular wave.wave.