The Energy of Waves Waves General and Electromagnetic.
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Transcript of The Energy of Waves Waves General and Electromagnetic.
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