The Energy ofThe Energy ofWavesWaves

WavesWavesGeneral and ElectromagneticGeneral and Electromagnetic

Nature of WavesNature of Waves

WavesWaves are disturbances are disturbances that transfer energy from place to that transfer energy from place to

place.place.

Energy can be carried away from Energy can be carried away from its source by a wave, but the its source by a wave, but the

medium does not move with the medium does not move with the energy. energy.

Wave TravelWave Travel

As waves move through media As waves move through media (such as a solid, liquid or gases) it (such as a solid, liquid or gases) it performs work by transferring performs work by transferring energy from one particle (atom) energy from one particle (atom) to another. to another.

Sound waves transfer energy by Sound waves transfer energy by vibration of particles in a vibration of particles in a medium. medium.

Sound WavesSound Waves

Require a medium Require a medium

to travel to travel

– – they vibrate particles. they vibrate particles.

Waves that require a medium are called Waves that require a medium are called

mechanical wavesmechanical waves..

Space is not a media (void of Matter)– Space is not a media (void of Matter)– therefore we cannot hear the therefore we cannot hear the explosion of a super nova – we can explosion of a super nova – we can only see it.only see it.

Electromagnetic WavesElectromagnetic Waves An

Electromagnetic Wave is a wave that can travel through empty space or matter and is produced by charged particles that are in motion.

ForcesForces

All All MatterMatter (Atoms - Protons & (Atoms - Protons & Electrons) exert Electrons) exert positivepositive and and negative chargesnegative charges creating an creating an Electrical Field.Electrical Field.

Thus - this Thus - this Electric Field (E)Electric Field (E) exerts a exerts a force on all other charged particles force on all other charged particles that are in a field. that are in a field.

ForcesForcesThe electromagnetic wave is made of

two parts—an electric field and a magnetic field. These fields are force fields.

A force field enables an object to exert forces on other objects, even though they are

not touching.

Forces - MagneticForces - MagneticJust as gravitational

field exerts a force on a mass, a magnetic field exerts a force on another magnet and on magnetic materials.

Magnetic fields cause other magnets to line up along the direction of the magnetic field

EarthquakesEarthquakes

3 Types of Mechanical 3 Types of Mechanical WavesWaves

Primary waves (P Waves)Primary waves (P Waves)

Cause particles in rocks to move Cause particles in rocks to move back andback and

forth in the same direction that the forth in the same direction that the wave iswave is

traveling.traveling.

3 Types of Mechanical 3 Types of Mechanical WavesWaves

Secondary Waves (S – Waves)Secondary Waves (S – Waves)

Causes particles in rocks to move at Causes particles in rocks to move at rightright

angles to angles to

the directionthe direction

of the waveof the wave

travel.travel.

3 Types of Mechanical 3 Types of Mechanical Waves Waves

Surface WavesSurface Waves

Causes rock particles in a backward, Causes rock particles in a backward, rollingrolling

motion and motion and

side-to-side, side-to-side,

swaying swaying

motion. motion.

WavesWavesWaves carry Waves carry energyenergy & & informationinformation

WAVES WAVES

DO NOTDO NOT

CARRY CARRY

THETHE

MEDIUM!!!MEDIUM!!!

Wave Energy canWave Energy canprovide informationprovide informationsuch as:such as:

SoundSound ColorColor PicturesPictures

Radio waves – tvRadio waves – tv

Microwave – cell Microwave – cell phonesphones

Wavelength Wavelength (( )Lambda: )Lambda:

The length of one complete cycle of The length of one complete cycle of a wave is from a wave is from crest to crestcrest to crest or or trough to trough.trough to trough.

AmplitudeAmplitudeHow high the wave rises above, or falls

below, the normal level is called the wave’s amplitude.

The amplitude of a transverse wave is one-half the distance between a crest and a trough

Higher the wave – the greater the energy.

FrequencyFrequency

How many waves pass How many waves pass in 1 sec.in 1 sec.

The faster the vibration is, the higher the frequency is of the wave that is produced.

Measured Unit in hertz Measured Unit in hertz (Hz)(Hz)

Wave SpeedWave Speed How fast the wave can How fast the wave can transfer energy.transfer energy.

How fast the wave can How fast the wave can transfer energy.transfer energy.

v = f x v = f x

v = speed (velocity) v = speed (velocity) Units=m/sUnits=m/s

f = frequency Units=Hzf = frequency Units=Hz = wavelength = wavelength

Units=mUnits=m

Longitudinal WavesLongitudinal Waves

Wave and energy Wave and energy are in same are in same directiondirection Ex: SlinkyEx: Slinky The The

compression compression will move along will move along the slinky the slinky forward and forward and then back.then back.

SoundSound

Also called Compressional Waves requires a Media

Longitudinal Wave Longitudinal Wave Parts Parts CompressionCompression-The condensed portion-The condensed portion

RarefactionRarefaction-The separated part of -The separated part of the wave.the wave.

WavelengthWavelength-distance from -distance from compression to compressioncompression to compression

Do not require a MediumDo not require a Medium

Visible Visible LLightight does not require media. does not require media.

They are They are Electromagnetic WavesElectromagnetic Waves..Examples: microwaves, X-Rays, TV Examples: microwaves, X-Rays, TV

and radio waves. and radio waves.

Natural WavesNatural Waves::Even though electromagnetic waves Even though electromagnetic waves

do not require a media they can do not require a media they can travel through space, air, water, and travel through space, air, water, and glass. glass.

Electromagnetic WavesElectromagnetic Waves

Sun light travels through space, air and Sun light travels through space, air and water to warm our planet and sustain water to warm our planet and sustain life.life.

Electromagnetic wavesElectromagnetic waves travels fastest travels fastest

through space.through space.

the speed of light = 299 792 458 m / s the speed of light = 299 792 458 m / s usually stated as usually stated as 300, 000 km/s300, 000 km/s

or 983,571,056 or 983,571,056 feet per second

Electromagnetic WavesElectromagnetic Waves

Waves in the electromagnetic Waves in the electromagnetic spectrum vary in size from very spectrum vary in size from very long long radio wavesradio waves the size of buildings, to the size of buildings, to very short gamma-raysvery short gamma-rays smaller than smaller than the size of the nucleus of an atom.the size of the nucleus of an atom.

Electromagnetic WaveElectromagnetic Wave

All electromagnetic radiation has All electromagnetic radiation has fundamental properties and behaves fundamental properties and behaves in predictable ways according to the in predictable ways according to the basics of wave theory.basics of wave theory.

Electromagnetic radiation consists of Electromagnetic radiation consists of an electrical field an electrical field (E)(E) which varies in which varies in magnitude in a direction magnitude in a direction perpendicular to the direction in perpendicular to the direction in which the radiation is traveling, and which the radiation is traveling, and a magnetic field a magnetic field (M)(M) oriented at right oriented at right angles to the electrical field. Both angles to the electrical field. Both fields travel at the speed of light (c).fields travel at the speed of light (c).

Electromagnetic RadiationElectromagnetic Radiation

Transverse WavesTransverse Waves

Wave and energy move Wave and energy move perpendicular perpendicular to each other. to each other. (90 degrees)(90 degrees)

The wave travels to the right as the The wave travels to the right as the oscillation points move up and down.oscillation points move up and down.

Transverse WavesTransverse WavesEnergy moves left to Energy moves left to

right as right as

waves moves up & waves moves up & downdown

Ex: water wavesEx: water waves

A Rope that is A Rope that is

moved up moved up

and down and down

LightLight

Transverse WavesTransverse WavesTRANSVERSE WAVESTRANSVERSE WAVES!!!!!!!!

All travel at the same speedAll travel at the same speed

The difference is in the frequency and The difference is in the frequency and the wavelength. the wavelength.

If one goes up, the other goes down.If one goes up, the other goes down.

Crests: high point of the Crests: high point of the wavewave

Troughs: low point of the Troughs: low point of the wavewave

Parts of A Transverse Wave

Parts of the EM Parts of the EM SpectrumSpectrum

Radio Waves-Radio Waves-Longest Longest wavelength, wavelength, lowest energy, lowest energy, lowest lowest frequencyfrequency..

Used for TV’s, Used for TV’s, Radios and Cell Radios and Cell PhonesPhones

Example: Radio Waves - Example: Radio Waves - EcholocationEcholocation

Radar:Radar:

RAdio Detecting and RAdio Detecting and Ranging Ranging

Radar first used In Radar first used In WWII WWII

EcholocationEcholocation is used is used by bats, dolphins by bats, dolphins and many whalesand many whales

MicrowavesMicrowavesA form of radio waves-some books A form of radio waves-some books

place them separately and some put place them separately and some put them in with radio.them in with radio.

They are the highest frequency (most They are the highest frequency (most energy) of the radio waves.energy) of the radio waves.

Infrared (IR)Infrared (IR)HeatHeat

Used to find people Used to find people in the woods.in the woods.

Infrared film Infrared film detects how hot detects how hot something is.something is.

Used to detect Used to detect cancercancer

Beneath redBeneath red

Visible Visible LightLight

ROY G. BIV-colors ROY G. BIV-colors of visible light.of visible light.

Sunlight emits UV Sunlight emits UV along with other along with other rays.rays.

Vitamin DVitamin D Too much Too much

harmful.harmful. Mostly filtered by Mostly filtered by

ozone.ozone. Red is longest Red is longest

wavelengthwavelength

Visible LightVisible Light

Ultraviolet RadiationUltraviolet Radiation

Main source is Main source is sunlightsunlight

Helps your body Helps your body produce vitamin Dproduce vitamin D

Overexposure = Overexposure = burns and skin cancerburns and skin cancer

Sunscreen helps to Sunscreen helps to blockblock

Beyond violetBeyond violet

X-rays and Gamma X-rays and Gamma RaysRays

X-rays-See bones.X-rays-See bones. High EnergyHigh Energy Use lead to block!Use lead to block! Gamma rays-Gamma rays-

highest energyhighest energy Used to treat Used to treat

cancercancer Generated by Generated by

radioactive atomsradioactive atoms

Wave InteractionsWave Interactions Interaction -Waves run into Interaction -Waves run into

other objects or another waveother objects or another wave Interaction can Interaction can increaseincrease or or

decreasedecrease wave energy wave energy Interaction can change the Interaction can change the

properties of the waveproperties of the wave Interaction can change the Interaction can change the

directiondirection

ReflectionReflection A wave bouncing A wave bouncing

off of a surfaceoff of a surface MirrorMirror Wave hitting a Wave hitting a

wallwall Incident wave – Incident wave –

moving to surfacemoving to surface Reflected wave – Reflected wave –

moving away from moving away from surfacesurface

ReflectionReflection

ReflectionReflection

RefractionRefraction

Bending of wave Bending of wave as it changes as it changes speedspeed

Speed changes Speed changes from on medium from on medium to anotherto another Air to waterAir to water Water to oilWater to oil

RefractionRefraction

RefractionRefraction

DiffractionDiffraction

Bending Bending of a wave when it comes into of a wave when it comes into contact with the edge of another objectcontact with the edge of another object

Light bending around a doorLight bending around a door

Diffraction – Sound WavesDiffraction – Sound Waves

InterferenceInterference

The result of two or more waves The result of two or more waves overlapping each other.overlapping each other.

When sound waves from several When sound waves from several instruments combine the wave instruments combine the wave produces a higher amplitude thus a produces a higher amplitude thus a louder sound louder sound

InterferenceInterference

The effect of 2 or more waves The effect of 2 or more waves interactinginteracting

Can be constructive or destructiveCan be constructive or destructive

Constructive Constructive InterferenceInterference

Wave crest come together at Wave crest come together at the same location.the same location.

Waves join together to make aWaves join together to make a

larger larger

wave.wave.

Constructive WavesConstructive Waves Increased AmplitudeIncreased Amplitude

Destructive InterferenceDestructive InterferenceThe crest of one wave meets the trough of The crest of one wave meets the trough of

another waveanother wave

Crest and trough subtract from each other Crest and trough subtract from each other to make a smaller waveto make a smaller wave

Sometimes Sometimes

the the

interference interference

cancels both cancels both

waveswaves

Destructive WaveDestructive Wave

Decreased AmplitudeDecreased Amplitude

Standing WaveStanding Wave

Is a wave that forms a stationary Is a wave that forms a stationary pattern in which portions of the pattern in which portions of the wave are at the rest position wave are at the rest position due to total destructive due to total destructive interference and other portions interference and other portions have a large amplitude due to have a large amplitude due to constructive interference.constructive interference.

Standing WaveStanding Wave

ResonanceResonanceAll objects have a frequencyAll objects have a frequency or set of or set of

frequencies with which they naturally resonate frequencies with which they naturally resonate when struck, plucked, strummed or somehow when struck, plucked, strummed or somehow disturbed. Each of the natural frequencies at disturbed. Each of the natural frequencies at which an object vibrates is associated with a which an object vibrates is associated with a standing wave pattern. When an object is standing wave pattern. When an object is forced into resonance vibrations at one of its forced into resonance vibrations at one of its natural frequencies, it vibrates in a manner natural frequencies, it vibrates in a manner such that a standing wave is formed within the such that a standing wave is formed within the object. So the natural frequencies of an object object. So the natural frequencies of an object are merely the harmonic frequencies at which are merely the harmonic frequencies at which standing wave patterns are established within standing wave patterns are established within the object. the object.

ResonanceResonance

DopplerDoppler Effect Effect SoundSound Change in Change in

frequency and frequency and pitch of a soundpitch of a sound that is caused by that is caused by either the either the movement of the movement of the source or the source or the listenerlistener

AmbulanceAmbulance Race carRace car