Behavior of Behavior of WavesWaves

S8P4. Students will explore the wave nature of sound and electromagnetic radiation.

a. Identify the characteristics of electromagnetic and mechanical waves.

d. Describe how the behavior of waves is affected by medium (such as air, water, solids).

f. Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch.

What is a wave?What is a wave?

A disturbance that A disturbance that transfers transfers energyenergy through through mattermatter or or spacespace..

Waves carry Waves carry energyenergy NOT NOT MATTERMATTER!!

What is a medium?What is a medium?The The mattermatter that the that the waves travel through.waves travel through.

Solid, Solid, liquidliquid, gas, gasThe The mediummedium does not does not travel with the wave.travel with the wave.

What is a mechanical What is a mechanical wave?wave?

A wave that has to have A wave that has to have mattermatter to travel. to travel.

Ex. Ex. SoundSound

What is an What is an electromagnetic wave?electromagnetic wave?

Waves that do Waves that do notnot require a require a mediummedium to to travel.travel.

They can travel the They can travel the fastest through fastest through spacespace..

What are two types of What are two types of waves?waves?

CompressionalCompressional Wave Wave

& &

TransverseTransverse Wave Wave

What is a What is a compressional compressional

(longitudinal) wave?(longitudinal) wave?

Matter in the medium Matter in the medium moves moves backback and and forthforth in the same in the same directiondirection that the wave travels. that the wave travels.

What are the parts of a What are the parts of a compressional wave?compressional wave?

CompressionCompression – particles are – particles are crowded together (more crowded together (more dense region)dense region)

RarefactionRarefaction – particles are – particles are spread further apart (less spread further apart (less dense region)dense region)

What is an example of What is an example of a compressional wave?a compressional wave?

SoundSound travels travels by by compressions compressions and and rarefactions.rarefactions.

What is a transverse What is a transverse wave?wave?

A wave in which the A wave in which the motion of the medium motion of the medium is at is at rightright angles to the angles to the directiondirection of the wave. of the wave.

How do you label a How do you label a transverse wave?transverse wave?

What are some wave What are some wave parts?parts?

Crest – highest point

Trough – Lowest point

What is the amplitude?What is the amplitude?The maximum distance The maximum distance the molecules are the molecules are displaceddisplaced from their rest from their rest position. (position. (HeightHeight of the of the wave.)wave.)

Amplitude. . . Amplitude. . .

What is the What is the relationship between relationship between

amplitude and energy?amplitude and energy?The The moremore energy the energy the wave has the wave has the higherhigher the the amplitude (taller the amplitude (taller the wave).wave).

What is wavelength?What is wavelength?The The distancedistance between one between one

point on a wave to one point point on a wave to one point just like it. just like it.

CrestCrest to Crest ( to Crest (TroughTrough to to Trough)Trough)

CompressionCompression to to Compression (Rarefaction to Compression (Rarefaction to Rarefaction)Rarefaction)

WavelengthWavelength

What is frequency?What is frequency?

The number of The number of wavelengthswavelengths that pass a that pass a fixed point each fixed point each secondsecond. . (Unit = Hertz (Hz). (Unit = Hertz (Hz).

How are frequency and How are frequency and energy related?energy related?

MoreMore energy, the energy, the higherhigher frequency. frequency.

It takes more energy for It takes more energy for a wave to vibrate quickly.a wave to vibrate quickly.

What is wave speed What is wave speed dependent upon?dependent upon?

A wave will move A wave will move slowerslower in in a a densedense medium. medium.

It is harder to get a It is harder to get a densedense medium to respond to the medium to respond to the energy of the wave.energy of the wave.

How do you calculate How do you calculate speed?speed?

Speed = frequency x wavelengthSpeed = frequency x wavelength m/s Hz mm/s Hz m

V = f x

What would happen if waves What would happen if waves encountered a different encountered a different

medium, reached another medium, reached another obstacle, or met another obstacle, or met another

wave?wave?Wave Behaviors : Wave Behaviors :

Reflection, Refraction, Reflection, Refraction, Diffraction, InterferenceDiffraction, Interference

What is reflection?What is reflection?

The The bouncingbouncing back of back of waves after striking an waves after striking an object.object.

What is refraction?What is refraction?The The bendingbending of waves due of waves due

to a change in to a change in speedspeed when traveling in different when traveling in different mediums.mediums.

Ex. Pencil in waterEx. Pencil in water

What is Diffraction?What is Diffraction?

Occurs when an Occurs when an objectobject causes a causes a wave to change and wave to change and bendbend around it. around it.

What is interference? What is interference? When When twotwo or more or more waveswaves arrive at the arrive at the same time.same time.

Constructive and Constructive and DestructiveDestructive

Constructive Constructive interference. . .interference. . .

When the When the crestcrest of of one wave meets the one wave meets the crestcrest of another of another (trough to trough)(trough to trough)

Destructive Destructive Interference. . .Interference. . .

When the When the crestcrest of of one wave meets the one wave meets the troughtrough of another. of another.