WaveWavea a disturbance disturbance that propagatesthat propagates

through a material through a material mediummedium or or spacespace..

Waves Waves transfer energytransfer energy without withoutthe bulk transport of matter.the bulk transport of matter.

In order for a In order for a mechanical wavemechanical wave to to exist, exist, energyenergy is needed to create is needed to create

a a disturbancedisturbance in an in an elastic elastic mediummedium..

All e/m wavesAll e/m waves travel through freetravel through freespace at a speed of approximatelyspace at a speed of approximately

3.00 x 103.00 x 1088 m/s m/s oror 186,000 miles/sec 186,000 miles/sec..

This speed is known as theThis speed is known as the speed of lightspeed of light..

Light, radio, x-rays, and gamma raysLight, radio, x-rays, and gamma raysare some examples of e/m waves. are some examples of e/m waves.

No medium is needed forNo medium is needed forELECTROMAGNETICELECTROMAGNETIC waves.waves.

The displacement of the particlesThe displacement of the particlesof the medium isof the medium is perpendicularperpendicular totothe direction of wave propagation.the direction of wave propagation.

TRANSVERSETRANSVERSE

LONGITUDINALLONGITUDINAL

The displacement of the particlesThe displacement of the particlesof the mediumof the medium isis parallelparallel to theto thedirection of wave propagation.direction of wave propagation.

Click here and here

to view simulations oftransverse and longitudinal waves.

SURFACESURFACE

A A combinationcombination of oftransverse transverse and and longitudinallongitudinal..

AmplitudeAmplitudethe the maximum displacementmaximum displacement

of a particle of the medium fromof a particle of the medium fromthe rest or equilibrium positionthe rest or equilibrium positiondenoted by A and measured in units of lengthdenoted by A and measured in units of length

PhasePhaserelated to the related to the position and motionposition and motion

of the particles of the mediumof the particles of the medium

• If the wave form has been “shifted left,” then If the wave form has been “shifted left,” then the phase is the phase is positivepositive..

• If the wave form has been “shifted right,” then If the wave form has been “shifted right,” then the phase is the phase is negativenegative..

WavelengthWavelengththe the shortest distanceshortest distance

betweenbetweentwo points that are “in two points that are “in

phase”phase”denoted by denoted by and measured in units of length and measured in units of length

FrequencyFrequency- - the number of complete the number of complete vibrations per unit timevibrations per unit time

denoted by f and measured in units of Hzdenoted by f and measured in units of Hz

PeriodPeriod - - the shortest the shortest timetime interval during interval duringwhich the motion of the wave repeats itselfwhich the motion of the wave repeats itself

denoted by T and measured in units of timedenoted by T and measured in units of time

T = 1/f

& f = 1/T

VelocityVelocity - the - the speedspeed of the wave of the wave

denoted by v and measured in units of dist/timedenoted by v and measured in units of dist/time

v = d/t = /T = f

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

Explore water Explore water waves using the waves using the

National National Geographic Wave Geographic Wave Simulator (link).Simulator (link).

Explore waves on a Explore waves on a spring using the spring using the wave simulator wave simulator found here.found here.

ReflectionReflection

the the turning backturning back of a wave when of a wave whenit reaches the it reaches the boundaryboundary of the of the

medium through which it is travelingmedium through which it is traveling

Law of ReflectionLaw of Reflection

the the angle of incidenceangle of incidence is is equalequalto the to the angle of reflectionangle of reflection

There are two types of reflection.

Fixed-end TerminationFixed-end Terminationthe reflected wave is

inverted when it reflectsfrom a more dense medium

Free-end TerminationFree-end Terminationthe reflected wave is

upright when it reflectsfrom a less dense medium

the bendingbending of a wave as it passes obliquelyobliquely from

one medium into another of different propagation different propagation

speedspeed

RefractioRefractionn

For refraction to occur, the waveFor refraction to occur, the wavemust change speed and must entermust change speed and must enterthe new medium at an oblique angle.the new medium at an oblique angle.

DiffractionDiffractionthethe spreadingspreading of a of a

wavewavearound a barrier oraround a barrier orthrough an openingthrough an opening

InterferenceInterferencethe result of the the result of the superpositionsuperposition

of two or more wavesof two or more waves

Superposition PrincipleSuperposition Principle

the displacement of the medium whenthe displacement of the medium whentwo or more waves pass throughtwo or more waves pass through

it at the same time is the it at the same time is the algebraicalgebraicsumsum of the displacements caused of the displacements caused

by the individual wavesby the individual waves

ConstructiveConstructiveresults in a larger amplitudelarger amplitude

Types of InterferenceTypes of Interference

DestructiveDestructiveresults in a smaller amplitudesmaller amplitude

Read more about interference Read more about interference here.

Click Click here to view the interferencepattern resulting from the superpositionpattern resulting from the superposition

of two transverse waves.of two transverse waves.

Click Click here and here to viewsimulations of the interference of

two circular waves.

You can view reflection,You can view reflection,refraction, diffraction,refraction, diffraction,and interference using bothand interference using bothplane and circular waves.plane and circular waves.

Click Click here to view a movieclip of an actual ripple tank experiment.clip of an actual ripple tank experiment.

The ripple tankThe ripple tanksimulation foundsimulation foundhere can be usedto investigateto investigatewave properties.wave properties.

A standing wavestanding wave is theresult of two wave trains of the same

wavelength, frequency, and amplitudetraveling in opposite directions

through the same medium.

Learn more about standing waveshere, here, and here.

Click here to view a simulation of theinterference of two traveling wavesthat can result in a standing wave.

Click here to view a simulationof standing waves on a string.

Standing waves may be produced easily inwater, string, and air columns.

Doppler EffectDoppler Effectthe change in frequency due to the relativethe change in frequency due to the relativemotion of the wave source and the observermotion of the wave source and the observer

The The observed frequencyobserved frequency is is higherhigher when when thethe

source and observer are getting source and observer are getting closercloser..

The The observed frequencyobserved frequency is is lowerlower when when thethe

source and observer are getting farther source and observer are getting farther awayaway..

Click here, Click here, here, here, and hereto run simulations of the Doppler Effect.to run simulations of the Doppler Effect.

The Doppler EffectThe Doppler Effectcan be evident forcan be evident forall types of waves –all types of waves –including light,including light,sound, water, etc…sound, water, etc…