Ch 11 - VocabularyCh 11 - Vocabulary wave, wave, medium, medium, transverse wave, transverse wave, longitudinal wave, longitudinal wave, Standing waveStanding wave crest, crest, trough, trough, Rest positionRest position Equilibrium positionEquilibrium position AmplitudeAmplitude wavelength, wavelength,

frequency, frequency, PeriodPeriod vibration, vibration, hertz, hertz, velocity, velocity, interference, interference, constructive constructive

interference, interference, destructive interferencedestructive interference Doppler EffectDoppler Effect ResonanceResonance ReflectionReflection refractionrefraction

Interactions of Interactions of WavesWavesSection 11-2Section 11-2

Two-Column NotesTwo-Column Notes

5 Types of Wave Interaction

ReflectionRefractionDiffractionResonanceInterference

Slide 1Slide 1

ReflectionReflection When a wave hits a When a wave hits a surface through which surface through which it cannot pass and it cannot pass and bounces backbounces back

Angle of incidence Angle of incidence equals angle of equals angle of reflectionreflection

Angle of incidence is Angle of incidence is angle between angle between incoming wave and incoming wave and perpendicular lineperpendicular line

MAIN IDEA DETAILS

ReflectionReflection

Angle ofIncidence

Angle ofReflection

Barrier

Slide 2Slide 2

What is RefractionWhat is Refraction When a wave moves When a wave moves from one medium to from one medium to another medium at an another medium at an angle, it changes angle, it changes speed, causing it to speed, causing it to bendbend

MAIN IDEA DETAILS

RefractionRefraction

Angle ofIncidence

Angle ofReflection

Slide 3Slide 3

What is Diffraction?What is Diffraction? When a wave passes a When a wave passes a barrier or moves barrier or moves through a hole in a through a hole in a barrier, it bends and barrier, it bends and spreads out.spreads out.

MAIN IDEA DETAILS

DiffractionDiffraction

Diffraction Animations

Slide 7Slide 7

What is Resonance?What is Resonance? All objects have a All objects have a ‘natural’ frequency.‘natural’ frequency.

Resonance occurs Resonance occurs when vibrations when vibrations traveling through an traveling through an object match its object match its ‘natural frequency’.‘natural frequency’.

The object starts to The object starts to vibrate at its ‘natural vibrate at its ‘natural frequency’.frequency’.

MAIN IDEA DETAILS

Resonance

An object causes a nearby object to vibrate at its

natural frequency, results in sound being amplified

Example

When you pluck a guitar string and it vibrates at its

natural frequency, the sound is louder

Slide 4Slide 4

What is Interference?What is Interference?

What is Constructive What is Constructive Interference?Interference?

When 2 or more waves When 2 or more waves meet and have an meet and have an effect on each other.effect on each other.

Occurs when two Occurs when two waves combine and waves combine and ‘match up’ to create a ‘match up’ to create a bigger amplitude.bigger amplitude.

MAIN IDEA DETAILS

Constructive InterferenceConstructive Interference

Wave 1

Wave 2

Resulting Wave

Slide 5Slide 5

What is Destructive What is Destructive Interference?Interference?

What is a Standing What is a Standing Wave?Wave?

When two waves When two waves combine on opposite combine on opposite trough/Crest and the trough/Crest and the waves cancel out.waves cancel out.

When an incoming When an incoming wave and reflected wave and reflected wave meet and the wave meet and the combined wave combined wave appears to be standing appears to be standing still.still.

MAIN IDEA DETAILS

Destructive InterferenceDestructive Interference

Wave 1

Wave 2

Resulting Wave

Standing WaveStanding Wave

Slide 6Slide 6

What is a ‘Node’ and What is a ‘Node’ and Antinode?Antinode?

Node: Where ingoing Node: Where ingoing and outgoing waves and outgoing waves meet and destructive meet and destructive interference causes an interference causes an amplitude of Zero.amplitude of Zero.

AntiNode: where the AntiNode: where the crest and trough of the crest and trough of the standing wave existstanding wave exist

MAIN IDEA DETAILS

Interference Animations

Constructive Interference

Destructive Interference

Effects of interference

Interference of light waves produces colors

Interference of sound waves produces beats

STANDING WAVES

A standing wave is a wave that is caused by

interference and appears to not be moving. It has

regions of no vibration and regions of maximum

vibration.

Standing waves do not move through a

medium, they cause the medium to vibrate in a loop or series of loops.

NODE - Area in wave of no vibration

ANTINODE – Area in wave of maximum vibration (midway between nodes

Standing waves occur at frequencies that are multiples

(harmonics) of the natural frequency of the string. The

natural frequency is the frequency the object tends to

vibrate at when disturbed.

Behavior of Waves- Doppler Effect

The observed change in Frequency of a wave when the source or observer is moving

HOMEWORK PROJECTHOMEWORK PROJECT DUE 4/13/09: DUE 4/13/09: Design and construct a musical instrument that Design and construct a musical instrument that

can play at least 3 different notes. can play at least 3 different notes. Be prepared to explain how your instrument creates Be prepared to explain how your instrument creates

sounds, and demonstrate to the class by playing your sounds, and demonstrate to the class by playing your instrument and singing a song along with the instrument and singing a song along with the demonstration. demonstration.

You may have one (1) partner. If you make a wind You may have one (1) partner. If you make a wind instrument, one person has to play while the other sings instrument, one person has to play while the other sings or you have to get a friend to sing while you play. or you have to get a friend to sing while you play.

REMEMBER: This is not music class, so you are REMEMBER: This is not music class, so you are not graded on the artistic value of your not graded on the artistic value of your presentation, only that you did it. See attached presentation, only that you did it. See attached grading handout.grading handout.