Goal for this unit: Goal for this unit: Explain that earthquakes, light and Explain that earthquakes, light and sound are all types of waves with sound are all types of waves with unique properties and that there are unique properties and that there are differences and similarities between differences and similarities between electromagnetic and mechanical waves. electromagnetic and mechanical waves. Pre-knowledge Level: Pre-knowledge Level: ?/33 ?/33 Please write three actions you plan Please write three actions you plan to do to be successful in this unit: to do to be successful in this unit: Ask for help when needed, review notes Ask for help when needed, review notes and and handouts on a regular basis, focus in handouts on a regular basis, focus in class. class.
Transcript
Goal for this unit: Goal for this unit: Explain that earthquakes, light and sound are Explain that earthquakes, light and sound are
all types of waves with unique properties and all types of waves with unique properties and that there are differences and similarities that there are differences and similarities between electromagnetic and mechanical between electromagnetic and mechanical waves.waves.
Pre-knowledge Level: Pre-knowledge Level: ?/33?/33 Please write three actions you plan to do to be Please write three actions you plan to do to be
successful in this unit:successful in this unit:
Ask for help when needed, review notes and Ask for help when needed, review notes and
handouts on a regular basis, focus in class. handouts on a regular basis, focus in class.
The Energy of WavesThe Energy of WavesLearning Goals:Learning Goals:
1.1. Describe how waves transfer energy.Describe how waves transfer energy.
2.2. Describe the difference between Describe the difference between transverse & longitudinal waves.transverse & longitudinal waves.
3.3. Describe the properties of amplitude, Describe the properties of amplitude, wavelength, and frequency.wavelength, and frequency.
4.4. Compare the properties of waves to the Compare the properties of waves to the wavelike property of energy in wavelike property of energy in earthquakes, light, and sound.earthquakes, light, and sound.
5.5. Describe how waves interact through Describe how waves interact through reflection, refraction, diffraction.reflection, refraction, diffraction.
Essential questionsEssential questions What is a wave?What is a wave? What is a medium?What is a medium? What is the difference between a What is the difference between a
longitudinal and transverse wave?longitudinal and transverse wave? What are the properties of a wave?What are the properties of a wave? What behaviors do all waves have in What behaviors do all waves have in
common?common? What is the difference between What is the difference between
reflection, refraction, and diffraction?reflection, refraction, and diffraction?
Nature of WavesNature of Waves WaveWave—any disturbance (movement) that —any disturbance (movement) that
transfers _______through transfers _______through ______________ or or empty empty ________________..
Waves move energy by ____________ Waves move energy by ____________ __________in a medium.__________in a medium.
MediumMedium—a substance a wave can travel —a substance a wave can travel through; it can bethrough; it can be____________________________________..
Characteristics of Waves: Sound wavesCharacteristics of Waves: Sound waves http://www.youtube.com/watch?v=8i6hTU0jw-g
energy matterspace
vibratingparticles
solid, liquid, or gas
Nature of WavesNature of Waves
Waves that do Waves that do NOTNOT need a medium are need a medium are called called __________________
__________ _____________ ___ Examples: Examples:
1.1. _______ _____________ ______
2.2. MicrowavesMicrowaves
3.3. x-raysx-rays
4.4. T.V. & radio wavesT.V. & radio waves
Waves that need a Waves that need a medium to move are medium to move are calledcalled _________ _________ ____________________________ExExamples:amples:
______________________ wave—the particles of the wave—the particles of the medium vibrate back and forth in the medium vibrate back and forth in the samesame direction the wave energy is moving.direction the wave energy is moving.
________________________ —part of a longitudinal wave —part of a longitudinal wave where the particles are where the particles are crowdedcrowded (pressed) (pressed) together together
Particles & Energy
Longitudinal
Compression
Wave animationsWave animations
http://www.youtube.com/watch?v=7cDAYFTXq3E
http://www.youtube.com/watch?v=JsJOug4SqL8
Properties of wavesProperties of waves
Amplitude—(wave height) distance from the rest position to the crest or trough
Large amplitude=more energy
crest
trough
rest position
Wavelength —the distance from any point on a wave to an identical point on the next wave.
(crest to crest, trough to trough, compression to compression, rarefaction to rarefaction)
Shorter wavelength=more energy
FrequencyFrequency —the number of —the number of __________________ passing through an area in one passing through an area in one ______________, , measured in measured in ______________ (Hz) (Hz)
Low frequency-few waves Per second
Higher frequency—more Waves per second
1 second
wavessecond
Hertz
1 Hertz = 1 wave per second1 Hertz = 1 wave per second 5 waves in 1 second= 5 Hz5 waves in 1 second= 5 Hz
Higher frequency= higher energyHigher frequency= higher energyWave speed— speed at which a wave Wave speed— speed at which a wave travels =frequency x wavelengthtravels =frequency x wavelength
Characteristics of Waves: Amplitude, Wavelength and Characteristics of Waves: Amplitude, Wavelength and Frequency Frequency http://www.youtube.com/watch?v=aif5mxf5DtU
Wave InteractionsWave Interactions ______________________—when a wave —when a wave _______ __ _______ __
_ _ ______ _ _____after hitting a barrier it can’t go after hitting a barrier it can’t go through.through.
Reflection bounces
back
echoAll types of waves All types of waves cancan be reflected be reflectedExample: Example: ______ ______ —a reflected sound —a reflected sound wave, sonarwave, sonar
Light waves Light waves reflectedreflected off an object allow off an object allow you to you to seesee it. it.
surface
__________________—the —the ________________ of light waves of light waves as they pass through from one medium to as they pass through from one medium to another at an angle.another at an angle.
Refraction bending
When a wave passes from one When a wave passes from one medium to another, it’s medium to another, it’s speed and speed and wavelengthwavelength changes so it changes so it __________________..Examples: Examples:
White light bends to form a rainbowWhite light bends to form a rainbow
bends
__________________—the change in direction of a —the change in direction of a wave as it bends around a barrier or wave as it bends around a barrier or openingopening
ResonanceResonance—when two objects vibrate at the —when two objects vibrate at the same frequency; one object same frequency; one object causes causes _____________________._____________________.
A A resonatingresonating object object absorbs energyabsorbs energy from the vibrating object and begins from the vibrating object and begins to to vibratevibrate too. too.The 4 month old bridge collapsed during a The 4 month old bridge collapsed during a windstorm with gusts that reached 68 km/h (42 windstorm with gusts that reached 68 km/h (42 mph). The catastrophe was attributed to faulty mph). The catastrophe was attributed to faulty design. Instead of allowing the wind to pass design. Instead of allowing the wind to pass through, the suspended girders caught the wind, through, the suspended girders caught the wind, causing the bridge to buck and roll. The bucking causing the bridge to buck and roll. The bucking motion earned the bridge the nickname Galloping motion earned the bridge the nickname Galloping Gertie. The stronger the wind blew, the more Gertie. The stronger the wind blew, the more violently the structure oscillated, until it finally violently the structure oscillated, until it finally broke apart and crashed into the water.broke apart and crashed into the water.
