waves what do you know?. types of waves mechanical need a medium or material to travel through ex....
DESCRIPTION
Transverse Waves The wave travels perpendicular to the motion of the The wave travels perpendicular to the motion of the matter being displacedTRANSCRIPT
WavesWaves
What do you What do you know?know?
Types of wavesTypes of waves• Mechanical – need a medium or Mechanical – need a medium or
material to travel through ex. Water, material to travel through ex. Water, slinkyslinky
• Electromagnetic- do not need Electromagnetic- do not need materials to travel ex. Xrays, lightmaterials to travel ex. Xrays, light
• Waves transmit energy through Waves transmit energy through space or materials space or materials
Transverse WavesTransverse Waves
• The wave The wave travels travels perpendicular perpendicular to the motion of to the motion of the the
matter being matter being displaceddisplaced
Anatomy of a waveAnatomy of a wave
• Six properties of Six properties of waveswaves
• FrequencyFrequency• WavelengthWavelength• Velocity Velocity • AmplitudeAmplitude• periodperiod
AMPLITUDEAMPLITUDE• Distance between the normal and Distance between the normal and
the top or bottom of a wave.the top or bottom of a wave.• The greater the amplitude, the The greater the amplitude, the
greater the energy of the wave or greater the energy of the wave or the greater the energy went in to the greater the energy went in to producing a wave. producing a wave.
• Ripple vs tsunamiRipple vs tsunami
FrequencyFrequency• The number of times a wave passes The number of times a wave passes
a point in a given time period.a point in a given time period.• Measure in hertz.Measure in hertz.• 1 hz = a cycle per second1 hz = a cycle per second
WavelengthWavelength• The distance between 2 crests or The distance between 2 crests or
troughs. troughs. • Long wavelengths usually mean low Long wavelengths usually mean low
frequencies frequencies
PeriodPeriod• Time it takes for a cycle or Time it takes for a cycle or
disturbance to occurdisturbance to occur• Time from crest to crest or trough to Time from crest to crest or trough to
trough trough • Period and frequency are determined Period and frequency are determined
by the source of that wave. They do by the source of that wave. They do not depend on the wave’s speed or not depend on the wave’s speed or the medium. the medium.
VelocityVelocity• The speed of a wave formulaThe speed of a wave formula• Velocity = wavelength X frequencyVelocity = wavelength X frequency• Velocity is determined by the material Velocity is determined by the material
that the wave is traveling through.that the wave is traveling through.• EX. Sound travels in water at a EX. Sound travels in water at a
different speed than in air.different speed than in air.• Temp and viscosity can effect velocity.Temp and viscosity can effect velocity.
SpeedSpeed• Sound travels at 343 m/s in air. Sound travels at 343 m/s in air.
Ex. problemsEx. problems• A sound wave has a frequency of 262 A sound wave has a frequency of 262
Hz and a wavelength of 1.29m. Hz and a wavelength of 1.29m. What is the speed of the wave?What is the speed of the wave?
Longitudinal waveLongitudinal wave• Particles Particles
vibrate vibrate parallel to the parallel to the motion of a motion of a wave as in wave as in earthquakes earthquakes and sound.and sound.
• CompressionsCompressions• rarefactionsrarefactions
Longitudinal wavesLongitudinal waves• Waves transmitted in fluids and air Waves transmitted in fluids and air
are longitudinalare longitudinal• This includes sound and water wavesThis includes sound and water waves• Water waves at the surface of water Water waves at the surface of water
have both longitudinal and have both longitudinal and transverse characteristics. These are transverse characteristics. These are known as surface waves. known as surface waves.
One of three things happens to One of three things happens to waves when they hit a barrier waves when they hit a barrier or change mediums.or change mediums.• ReflectionReflection• RefractionRefraction• DiffractionDiffraction
ReflectionReflection• All or part of a All or part of a
wave bounces back wave bounces back or returnsor returns
• The approaching The approaching wave is the wave is the incident waveincident wave
What happens when a wave What happens when a wave hits a more rigid barrier.hits a more rigid barrier.• The reflected waves comes back The reflected waves comes back
inverted or upside down.inverted or upside down.
What happens when a wave What happens when a wave enters a less rigid medium?enters a less rigid medium?• The reflected wave returns right side The reflected wave returns right side
up or erect. up or erect.
Law of ReflectionLaw of Reflection• Normal is Normal is
perpendicular perpendicular to surface of a to surface of a barrierbarrier
RefractionRefraction• Waves are bent Waves are bent
when they hit a when they hit a barrier or change barrier or change mediamedia
• Ex. Water wave on Ex. Water wave on the shorethe shore
• Light traveling Light traveling through glass through glass ( broken pencil trick)( broken pencil trick)
DiffractionDiffraction• When a wave When a wave
bends around a bends around a barrier.barrier.
Diffraction of water wavesDiffraction of water waves•http://www.smeter.net/propagation/d
iffrac1.php
InterferenceInterference• When 2 waves When 2 waves
traveling in traveling in opposing directions opposing directions cross one another cross one another interference occurs.interference occurs.
• These may cancel These may cancel one another out. one another out.
• Can you see where Can you see where interference occurs. interference occurs.
Constructive interferenceConstructive interference
Destructive interferenceDestructive interference
•
•
Polarization of a wave Polarization of a wave occurs when light is occurs when light is restricted to one plane. restricted to one plane.
Effect of a polarizer on reflection from mud flats. In the picture on the left, the Effect of a polarizer on reflection from mud flats. In the picture on the left, the polarizer is rotated to transmit the reflections as well as possible; by rotating polarizer is rotated to transmit the reflections as well as possible; by rotating the polarizer by 90° (picture on the right) almost all the polarizer by 90° (picture on the right) almost all specularly reflected
sunlight is blocked.sunlight is blocked.
Polarizing filmPolarizing film
•
Sound WavesSound Waves• LongitudinalLongitudinal• Their amplitude is measured in Their amplitude is measured in
decibels.decibels. This is a measure of their loudness.This is a measure of their loudness.Their frequency is heard as its pitch.Their frequency is heard as its pitch.Speed in air is 343 m/s.Speed in air is 343 m/s.
ResonanceResonance• Resonance is Resonance is
usually associated usually associated with sound waves. with sound waves.
• This occurs when This occurs when the vibrations of the vibrations of one object are one object are picked up by picked up by another and it another and it vibrates in sync. vibrates in sync.
PitchPitch• Pitch in sound waves refers to the Pitch in sound waves refers to the
frequency of the sound wave.frequency of the sound wave.
• Amplitude of a sound wave is Amplitude of a sound wave is measured in dedibels and refers to measured in dedibels and refers to the strength or energy of the waves. the strength or energy of the waves.
