Chapter 11 Types of WavesSection 11.1Section 11.1
WavesWaves A disturbance that A disturbance that transmits energy
through transmits energy through matter or spacematter or
space
WavesWaves Most waves move Most waves move through through
mattermatter called a called a mediummedium.. Ex. Waves traveling
Ex. Waves traveling through water. through water.
Types of WavesTypes of Waves 1. Mechanical Waves1. Mechanical Waves
a wave that requires a a wave that requires a medium through which
to medium through which to traveltravel Most type of wavesMost type
of waves
Ex.Ex. Sound, seismicSound, seismic
Types of WavesTypes of Waves 2. Electromagnetic Waves2.
Electromagnetic Waves waves caused by the waves caused by the
disturbance in electric and disturbance in electric and magnetic
fields and that magnetic fields and that does does not require a
mediumnot require a medium..
(light radiation waves)(light radiation waves)
What do Waves Do?What do Waves Do? When waves travel When waves
travel through media they are through media they are doing work
(energy doing work (energy transferred). transferred). Ex. Sound
traveling in your Ex. Sound traveling in your ear causes vibrates
ear causes vibrates throughout your earthroughout your ear
What do Waves Do?What do Waves Do? Ex. Shock waves move Ex. Shock
waves move the earth during an the earth during an
earthquake.earthquake. Ex. Tsunami waves move Ex. Tsunami waves
move anything in their pathanything in their path
Shock wave from breaking the Shock wave from breaking the sound
sound barriorbarrior..
How a Wave TravelsHow a Wave Travels As wave travels in air, the As
wave travels in air, the waves spread out in sphereswaves spread
out in spheres the sphere will get bigger the sphere will get
bigger and bigger as they move and bigger as they move farther
awayfarther away
How a Wave TravelsHow a Wave Travels
Why is it more damaging to Why is it more damaging to your ears if
you are your ears if you are standing next to a speaker standing
next to a speaker rather than a 100 meters rather than a 100 meters
away?away?
How a Wave TravelsHow a Wave Travels Each sphere carries the Each
sphere carries the same amount of energysame amount of energy But
the energy is more But the energy is more
spread outspread out
Speaker Sound waves
Vibrations and WavesVibrations and Waves Most waves are caused by
Most waves are caused by a vibrating object, which a vibrating
object, which will then cause other will then cause other objects
to vibrate objects to vibrate Vibrations will transfer Vibrations
will transfer energy from PE to KE.energy from PE to KE.
Vibrations and WavesVibrations and Waves simple harmonic
motionsimple harmonic motion---- vibration would continue
forevervibration would continue forever Damped harmonic
motionDamped harmonic motion transfers the energy and the transfers
the energy and the vibration will fade out.vibration will fade out.
Ex. Shock absorbers on cars and Ex. Shock absorbers on cars and
bikes.bikes.
Wave Vibration TypesWave Vibration Types 1. Transverse Waves1.
Transverse Waves
--a wave that causes the particles of the a wave that causes the
particles of the medium to vibrate perpendicular to medium to
vibrate perpendicular to the direction of the wave.the direction of
the wave. ““The WaveThe Wave”” at a stadium is a good at a stadium
is a good illustration. illustration. Ex. Light wavesEx. Light
waves
wave wave commericalcommerical
Wave Vibration TypesWave Vibration Types 2. Longitudinal Waves2.
Longitudinal Waves
--a wave that causes the particles of a wave that causes the
particles of the medium to vibrate parallel to the medium to
vibrate parallel to the direction of the wave.the direction of the
wave. they expand and compress.they expand and compress. Ex. Sound
wavesEx. Sound waves
Wave Vibration TypesWave Vibration Types 3. Surface Waves3. Surface
Waves
--waves that are both waves that are both transverse or
longitudinal. transverse or longitudinal.
--Circular motionCircular motion --ex. Ocean wavesex. Ocean
waves
Wave TypesWave Types
, or surface waves, or surface waves Electromagnetic
(light):Electromagnetic (light):
--waves will only be transverse.waves will only be
transverse.
Characteristics of Characteristics of WavesWaves
11.211.2
Wave PropertiesWave Properties all all transversetransverse waves
have waves have similar shapes, no matter similar shapes, no matter
the size of the wave. the size of the wave. The shape is called a
The shape is called a sine curvesine curve or or sine wave. sine
wave.
Sine WaveSine Wave
Wave PartsWave Parts CrestCrest Highest point of a Highest point of
a transverse wavetransverse wave TroughTrough lowest point of a
transverse lowest point of a transverse wavewave
Wave PartsWave Parts AmplitudeAmplitude
--The vertical distance that The vertical distance that particles
vibrate from their particles vibrate from their normal position
when a wave normal position when a wave passespasses measures the
intensity of wave.measures the intensity of wave.
--ex.ex.
Wave PartsWave Parts WavelengthWavelength
--The distance between any two The distance between any two
successive identical parts of a successive identical parts of a
wavewave Represented by the symbol Represented by the symbol lambda
(lambda (λλ)) Measured in a degree of metersMeasured in a degree of
meters
Wave DiagramWave Diagram
Wave PropertiesWave Properties 1. Wavelength1. Wavelength
--measures the size of the measures the size of the wavewave
Wave PropertiesWave Properties 2. Amplitude2. Amplitude
--measures the intensity measures the intensity (strength) of the
wave(strength) of the wave
Wave PropertiesWave Properties 3. Frequency3. Frequency
--the number of full wavelengths that the number of full
wavelengths that pass a point in a particular period pass a point
in a particular period of time (rate)of time (rate)
--Represented by the symbol (Represented by the symbol (ƒƒ))
--Measured in hertz (Hz) or beat/secMeasured in hertz (Hz) or
beat/sec --Your radio dials are in megahertzYour radio dials are in
megahertz
Wave PropertiesWave Properties 4. Period (time)4. Period
(time)
--The The timetime
required for one full required for one full wavelength to pass a
certain point wavelength to pass a certain point
--Represented by the symbol (T)Represented by the symbol (T)
--Measured in secondsMeasured in seconds
Wavelength
High
Low
Low
High
Frequency, wavelength, Frequency, wavelength, and Periodand
Period
Wavelength and period will Wavelength and period will increase when
frequency increase when frequency decreases.decreases. λλ ↓↓, T, ,
T, ↓↓, then , then f f ↑↑
Frequency and PeriodFrequency and Period
You can calculate You can calculate frequency and period from
frequency and period from each othereach other T=1/T=1/ff or or
ff=1/T=1/T
Frequency and SoundFrequency and Sound We hear sounds from the We
hear sounds from the range 20 Hz to 20,000 Hzrange 20 Hz to 20,000
Hz determines the determines the pitchpitch
Pitch and LoudnessPitch and Loudness
Frequency determines the energyFrequency determines the
energy
Red is the easiest to see, violet is Red is the easiest to see,
violet is the hottestthe hottest
Wave PropertiesWave Properties 5. Wave Speed5. Wave Speed --the
speed at which a wave the speed at which a wave passes through a
medium.passes through a medium.
--Waves travel at different Waves travel at different speeds in
different media speeds in different media phases (s, l, g).phases
(s, l, g).
Mechanical Wave SpeedMechanical Wave Speed These waves travel
fastest These waves travel fastest in solids and the slowest in in
solids and the slowest in gasesgases Why? (essay question)Why?
(essay question)
sonic boom
Wave Speed EquationsWave Speed Equations
Speed=wavelength/periodSpeed=wavelength/period v=v=λλ/T/T
Can also use:Can also use: Speed=frequency x
wavelengthSpeed=frequency x wavelength v = v = ff x x λλ
ExamplesExamples A piano string vibrates with A piano string
vibrates with a frequency of 264 Hz. If a frequency of 264 Hz. If
the waves have a the waves have a wavelength of 1.3 m, what
wavelength of 1.3 m, what is the speed of sound in air?is the speed
of sound in air?
ExamplesExamples v= v= λλ ff
speed= (1.30 m) (264 Hz)speed= (1.30 m) (264 Hz) speed = 343
m/sspeed = 343 m/s
ExamplesExamples A string with aA string with a wavelength of 1.30
m andwavelength of 1.30 m and a period of 0.00379 s isa period of
0.00379 s is played. What is theplayed. What is the speed of the
wave?speed of the wave?
ExamplesExamples V = V = λλ/T/T speed=1.30 m/0.00379 sspeed=1.30
m/0.00379 s speed = 343 m/sspeed = 343 m/s
Doppler EffectDoppler Effect an observed change in the an observed
change in the frequency of a wave when the frequency of a wave when
the source or observer is movingsource or observer is moving Object
approaches with high Object approaches with high frequency but low
wavelength, but frequency but low wavelength, but as it passes the
frequency lowers as it passes the frequency lowers as the
wavelength increasesas the wavelength increases
1. Reflection1. Reflection
The bouncing back of a The bouncing back of a wave as it meets a
wave as it meets a surface or boundarysurface or boundary
InterferenceInterference Two types:Two types:
destructivedestructive
ConstructiveConstructive InterferenceInterference The crests of
wave line up The crests of wave line up to combine their to combine
their amplitudes making the amplitudes making the wave larger.wave
larger. Wave becomes biggerWave becomes bigger
ConstructiveConstructive InterferenceInterference The new wave is
The new wave is biggerbigger than the original when than the
original when waves combinewaves combine
DestructiveDestructive InterferenceInterference When crest of one
wave When crest of one wave meets the trough of another meets the
trough of another wave wave Forms a Forms a smallersmaller wave
than wave than the originalthe original
Interference of Light WavesInterference of Light Waves When light
waves interfere When light waves interfere with each other,
colorful with each other, colorful displays are produced.displays
are produced. Soap bubblesSoap bubbles
Interference of Sound WavesInterference of Sound Waves When two
waves with When two waves with different frequencies different
frequencies interfere with each other, interfere with each other,
beats are producedbeats are produced
Standing WavesStanding Waves wave that appears not to wave that
appears not to move along the medium.move along the medium. two
regionstwo regions
Standing WavesStanding Waves Regions of no vibrations Regions of no
vibrations (nodes)(nodes) Regions of maximum Regions of maximum
vibration vibration (antinodes)(antinodes)
Slide Number 13