2 A WAVE is:a disturbance that transmits energy through matter or space in a regular pattern.Most waves are caused by…vibrating matter or particles.A medium is: the matterthrough which a wavetravels; i.e. water, airTwo types of waves, mechanical and electromagnetic.
3 MECHANICAL WAVES 2 types - Longitudinal or transverse Examples: Require a medium!!2 types - Longitudinal or transverseExamples:Longitudinal: sound, spring wavesTransverse: water waves, some seismic wavesTurn the page and forget about Electromagnetic waves, we will get back to them.
5 Particle Movement and Parts of a Longitudinal wave Particles in the medium move parallel to the direction of the waves.The dense areas are called compressions.The less dense areas are rarefactions.Wavelength is measuring from compression to compression or rarefaction to rarefaction
7 Parts of a Transverse Wave crestwavelengthamplitudetrough
8 TransverseParticles in the medium move perpendicular to the direction of the waves.wave motionparticlemotion
9 Parts of a Wave Crest: the highest point (top) of a transverse wave. Trough: the lowest point (bottom) of a transverse wave.Wavelength: the distance from any point on a wave to the same point on the next wave. (ex: crest to crest)Amplitude: the height measured from the resting position.
13 ELECTROMAGNETIC WAVES (Turn back to page 1 to Complete the chart)Do not require a medium!! (Can travel in a vacuum like outer space.)7 types of Electromagnetic Waves- radio waves, microwaves, infrared rays, visible light, ultraviolet, x-rays, gamma raysModeled as transverse motion.(So they travel like ocean waves.)
14 Electromagnetic Waves Return back to the bottom of page 2
15 8.2 Wave Properties and Measurements AMPLITUDENot only is it the height of a wave but it measures the amount ofenergy in a wave.Greater amplitude = more energy.
16 WAVELENGTH PERIOD Symbol: Greek letter lambda, λ Tool: meterstick Unit: meter (m)PERIODTime it takes for a full wavelength to pass.Symbol: TTool: stopwatchUnit: seconds (s)
17 FREQUENCYThe rate at which waves pass (the # of full wavelengths that pass a point in 1 second).Symbol: fUnit: Hertz (Hz)1 Hertz = 1 vibration per secondFrequency is the inverse period1 / P
18 WAVE SPEED How fast a wave moves. Symbol: v Unit: m/s Wave speed is determined by the medium. Generally, waves pass through solids faster b/c particles are closer and can pass vibrations to each other more quickly.
19 WAVE SPEED cont. EX: Speed of sound in air: 340 m/s in water: 1490 m/s in iron: 5000 m/sAn exception is light, which travels slower in a medium than in empty space (vacuum).All electromagnetic waves travel at a speed of 3.0 x 108 m/s (186,000 mi/s) in a vacuum.
21 EQUATIONS v = f · λ f = v / λ λ = v / f v UNITS: λ = meters (m) Wave speed = frequency times wavelengthv = f · λf = v / λλ = v / fUNITS: λ = meters (m)f = Hertz (Hz)v = m/svf λ
22 The string of a piano that produces the note middle C vibrates with a frequency of 264 Hz. If the sound waves produces have a wavelength of 1.30 m in air, what is the speed of sound in air?Data Formula Work Ans
23 A water wave has a speed of 1. 3 m/s A water wave has a speed of 1.3 m/s. A person sitting on a pier observes that it takes 1.2 s for a full wavelength to pass the edge of the pier. What is the wavelength of the water wave?Data Formula Work Ans
24 8.3 Wave BehaviorAll electromagnetic waves travel at the speed of light in empty space.C = 3.0 X 108 m/s (186,000mi/s)Light travels slower through a medium.
25 The Doppler EffectAn observed change in the frequency of a wave when the source or observer is moving.The sound waves’ frequency and pitch are higher as the ambulance moves toward A.The sound waves’ frequency and pitch are lower as the ambulance moves away from the observer.Closer waves = high frequency, high pitchFrequency and Pitch are directly related.
26 DOPPLER EFFECT Pitch of a sound is determined by the wave’s frequency
27 Auto RacingSound waves from an approaching object are closer together than sound waves from the object when it is standing still. The speed of the approaching object determines how much closer the waves will be. The sound waves from an object going away are farther apart than the waves from the same object standing still. Again the speed of the object deter- mines how much farther apart the waves from the moving object are than those from the stationary object. A race fan standing by the track hears a high-pitched sound as a car approaches which changes suddenly to a lower pitch as the car passes and begins to move away. The amount of change in pitch is determined by the speed of the car. Fans with perfect pitch can clock a car reasonably accurately by listening to the pitch change in the sound of the engine as the car passes them.
28 ReflectionThe bouncing back of a wave as it meets a surface or boundary
29 ReflectionWhen a wave has a free boundary they reflect like the original waveWhen a wave has a fixed boundary they reflect upside downFree boundary Fixed boundary
30 DiffractionThe bending of a wave as it passes an edge or an opening
36 Constructive Interference When the crest of one wave overlaps the crest of another wave resulting in a new wave with an amplitude that is the sum (larger) of the 2 individual waves amplitudes.Resulting amplitude is larger.
37 Destructive Interference When the crest of one wave overlaps the trough of another and the resulting wave’s amplitude is smaller than the original 2 wave’s amplitudes.
38 Light InterferenceIridescence of peacock feathers is caused by light reflected from complex layered surface
39 Sound Interference – Interference of sound waves produce BEATS
40 White Noise?????Because white noise contains all frequencies, it is frequently used to mask other sounds.Example: If you are in a hotel and voices from the room next-door are leaking into your room, you might turn on a fan to drown out the voices.