WaveWaveare oscillations (repeating are oscillations (repeating disturbance or movement) disturbance or movement)

that that transfers energytransfers energy through through mattermatter or or spacespace..

Waves move due to the Waves move due to the movementmovement

of a of a vibrationvibration

from a from a sourcesource

through a through a mediummedium

longitudinal or compressional

transverse

pulse (single event)continuous (repeated events)

Physical matter for mechanical waves

Electric and magnetic fields for electromagnetic waves

Classification of Waves

Mechanical

Electromagnetic

Longitudinal

Transverse

Surface

Classification according to medium through which wave travels

Classification according to wave orientation

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.

Electric & magnetic fields are needed forElectric & magnetic fields are needed forELECTROMAGNETICELECTROMAGNETIC waves.waves.

Mechanical WavesThere are 3 types of mechanical waves.

– 1) transverse waves – 2) compressional waves or longitudinal waves– 3) surface waves

Electromagnetic Waves

Mechanical Waves

• Matter is the medium

• Sound is a mechanical wave

Electromagnetic Waves

• Electric and magnetic fields are the media

• Light is an electromagnetic wave

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.

Longitudinal • Longitudinal wave has

oscillations that travel parallel (same direction) to the direction of motion                   

• Made up of compressions and rarefactions in the medium that they are traveling in

• Examples: sound waves and s waves for earthquakes

Transverse Waves

• All electromagnetic waves are transverse. This includes light.

• Transverse wave: has its oscillations perpendicular to the direction of the wave. The wave moves left to right and the oscillation moves up and down

Click here, here, and hereto view simulations of

transverse and longitudinal waves.

SURFACESURFACE

A A combinationcombination of oftransverse transverse and and longitudinallongitudinal..

Ocean waves are an example of surface waves

Properties of Waves

• The properties of a waveforms are:

• wavelength (period)

• amplitude

• velocity

• frequency

• All periodic (repeating) waveforms have these common characteristics

WavelengthWavelengththe horizontal the horizontal distancedistance of of

one complete wave (crest to one complete wave (crest to crest or trough to trough)crest or trough to trough)

denoted by denoted by and measured in units of length (m) and measured in units of length (m)

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 position

denoted by A and measured in units of length (m)denoted by A and measured in units of length (m)

FrequencyFrequency- - the number of waves the number of waves that pass a given point in one secondthat pass a given point in one second

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 time (s)denoted by T and measured in units of time (s)

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/time (m/s)denoted by v and measured in units of dist/time (m/s)

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.

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

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

Click Click here to view these types of reflection.

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

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.

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 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…