unit 4 section 2 notes types of waves

Types of Waves

What is a Wave?Wave:

A disturbance that carries energy through matter or space.

Examples of Waves:Sound you hear from your headphones

EarthquakesRipples in a pond

MediumsA wave is not made of matter, but involves

the movement of matter. Most waves travel through a medium. Medium: the matter through which a wave

travels. Examples: Sound you hear from your headphones: AirEarthquakes: EarthRipples in a pond: Water

Types of WavesMechanical Waves:

Most waves are mechanical waves

They require a medium (like water or air) to travel through.

Types of WavesElectromagnetic

Waves:Do NOT require a

medium to travel through

Made of changing electric and magnetic fields, which radiate at the speed of light (3x108m/s)

This shows the wave traveling along one line, but it actually fills space.

Electromagnetic WavesAnything that is part of the electromagnetic

spectrum is an electromagnetic wave. That includes:Radio wavesMicrowavesInfraredVisible lightUltraviolet lightX-RaysGamma Rays

Types of WavesMechanical Waves Electromagnetic

Waves

Waves do WorkWe know that

waves carry energy because they can do work:Examples:

Water waves can do work on a leaf or a boat

Sound waves can do work on your eardrum

Waves do WorkThe larger the wave, the more

energy it carries.Example:

A cruise ship moving through the ocean may create waves big enough to move a fishing boat up and down a few meters.

Characteristics of WavesIf you go to a rock

concert and stand next to the speakers, the sound waves may damage your ears. But if you stand 100 m away, the sound of the rock band is harmless. Why?

As waves travel outward, the spherical wave fronts get bigger, so the energy spreads out over a larger area.

Transverse and Longitudinal WavesWaves are classified according to the

direction in which particles in the medium move as a wave passes by; they can either move up and down or back and forth.

They are classified as either transverse or longitudinal.

Transverse WavesTransverse wave: wave in which wave motion

is perpendicular (up and down) to particle motion. Examples:

A crowd doing “the wave”; individual people move up and down, but the motion travels around the stadium

Electromagnetic waves; electric and magnetic fields are perpendicular to each other

Motion of particles in a transverse waveWave travels to the right:

Wave motion

Particle motion

Longitudinal Waves (Compression Wave)Longitudinal waves: Waves in which wave motion

is parallel to the particle motion. Example: Sound waves; as they move through the air,

molecules in the air move backward and forward, parallel to the direction the sound waves travel.

Parts of WavesTransverse Waves Longitudinal WavesCrests: high points of

transverse wavesTroughs: low points of

transverse waves

Compressions: crowded areas of longitudinal waves

Rarefactions: stretched out areas of longitudinal waves

Surface WavesSome waves are not simply transverse or

longitudinal:Surface Waves: Waves that move both

perpendicular and parallel to the direction of wave motion. Example: Waves on the ocean or

swimming poolThis type of wave also occurs at the

boundary between 2 different mediums, like water and air.

Surface Waveshttp://www.acs.psu.edu/drussell/Demos/

waves/wavemotion.html http://www.teachersdomain.org/asset/

lsps07_int_waves/

Diagram of Types of Waves

Simple Harmonic MotionA vibration that can

keep on going without any interference.

Dampened Harmonic Motion:A vibration that

fades out as energy is transferred from one object to another