Wave Notes 8­6.1
Waves are a repeating disturbance, vibration, or movement that
transfers or moves energy from place to place.
Waves can carry energy through empty space or a medium without
transporting matter.
Pull
Energy is the ability to cause something to happen or change.
Pull
Waves transmit energy but not matter.
http://www.youtube.com/watch?v=7yPTa8qi5X8&feature=player_detailpage
Medium - material through which waves can travel.
A medium can be a solid, liquid, or gas, or a combination of these.
Pull
http://www.teachersdomain.org/assets/wgbh/ess05/ess05_int_wavemotion/index.html
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Types of Waves: 8­6.2
Electromagnetic waves involve electric and magnetic fields. They are
waves that can travel through empty space where matter is NOT
present. Electromagnetic waves transfer energy through space instead
of transferring energy from particle to particle as is done by
mechanical waves.
Ex. radio waves, microwaves, infrared rays, visible light, ultraviolet
rays, x-rays, and gamma rays.
Pull
Mechanical waves are waves that travel through matter. The particles
of matter vibrate by pushing together and moving apart, or by moving
up and down as the waves travel through them to transfer the energy
through the medium. They require particles to vibrate. Sound waves
cannot be transferred or transmitted through space. Why?
Ex. Sound waves, water waves, waves that travel down a rope.
Pull
Distinguish btw mechanical and electromagnetic waves.
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3
Frequency and wavelength are inversely proportional. As frequency increases, wavelength decreases.
Pull
Pull
Frequency ­ the number of full wavelengths that pass a point each second. The greater the energy carried by the wave, the greater the frequency.
Pull
Properties of Waves 8­6.3
Wavelength ­ the distance between one point on a wave and the nearest point just like it. the greater the energy carried by the wave, the shorter the wavelength.
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5
http://www.youtube.com/watch?feature=player_detailpage&v=
7Iv4GmyXsCQ
http://phet.colorado.edu/sims/wave­on­a­string/wave­on­a­string_en.html
http://www.falstad.com/wavebox/
http://www.youtube.com/watch?feature=player_embedded&v=d­
XbjFn3aqE
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Speed ­ the distance per time that a given wave travels. A particular type of wave has a wave speed that is constant in a specific medium or in space. As a wave enters a different medium, the wave's speed changes. Waves travel at different speeds in different mediums. All electromagnetic waves travel at the same speed in empty space ­ 300 million m/sec
Pull
Amplitude ­ the greatest that vibrations in a wave move from their normal position when a wave passes by. The greater the amplitude, the greater the energy.
Pull
Properties of Waves 8­6.3
http://utahscience.oremjr.alpine.k12.ut.us/sciber03/middle/8_sciber/forces/images/ampltude.gif
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Wave Motion (transverse wave)
Movement of particles
Transverse Wave -The particles of matter move back and
forth at right angles to the direction in which the wave
travels.
Direction of wave
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Pull
Pull
Parts of a Transverse Wave 10
11
Label the parts of the transverse wave by sliding the name next
to the part.
Crest
wavelength
trough
amplitude
Click here for Review game
correct answers
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Wave Motion (compressional wave)
Compressional Waves/ Longitudinal -cause particles in
matter to move similar to a push and pull along the same
direction in which the wave travels
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Pull
Pull
Parts of a Compressional Wave 14
http://www.youtube.com/watch?v=7cDAYFTXq3E
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Label the parts of the compressional wave by sliding the name
next to the part.
rarefaction
compression
amplitude
wavelength
Do student demo now.
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Pull
Types of mechanical and electromagnetic waves
Sound wave (compressional)
Rope wave (transverse)
Electromagnetic wave (transverse)
Ready to sing?!
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Wave Speed:
Wave Speed = frequency X wavelength
V = F λ
v = Phase speed or speed of the wave measured in m/s,
f = frequency of the wave measured in Hertz (Hz),
λ = (Lambda)wavelength of the wave
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Wave Behavior
Refraction - bending of waves caused by change in their speed as they pass
from one medium to another.
Reflection - the bouncing back of a wave when it meets a surface that does
not absorb the entire wave's energy.
Absorption - occurs when the energy is not transferred through the given
medium or space.
Transmission - occurs when waves pass through a given point or medium.
Match the term with the correct illustration
Absorption
Reflection
Refraction
Transmission
Answers
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Transmission depends on the material.
Opaque - absorbs most of the light.
Impenetrable by light.Ex. book, blanket
Translucent - transmits some light.
Transmitting light but not enough to distinguish
distinct images. Ex. sunglasses, wax paper
Transparent - all light passes through.
Transmits light so that objects can be seen as
if there were no material blocking the object.
Ex. glass, clear water
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Transmission of Light
Move the circle over one of the stars. Then, move the correct term next to the
image shown.
opaque
transparent
translucent
answers
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Homework Practice
1.Mac and Tosh are resting on top of the water near the end of the pool when Mac creates a surface wave. The wave travels the length of the pool and back in 25 seconds. The pool is 25 meters long. Determine the speed of the wave.
2. Two boats are anchored 4 meters apart. They bob up and down, returning to the same up position every 3 seconds. When one is up the other is down. There are never any wave crests between the boats. Calculate the speed of the waves.
3. Sound waves are longitudinal, but light waves are transverse. T/F
4. Light waves can travel through a vacuum, but sound waves require a medium. T/F
5. Transverse waves travel faster than longitudinal waves. T/F
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Frequency (HZ) Wavelength (m) Velocity (m/sec)
25 10 ____________
12 4 ____________
60 ____________ 240
___________ 1000 750
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Sound Waves and the Parts of the Ear
• Sound travels as a compressional wave.
• Sounds with greater amplitude will be louder; light with greater amplitude will be brighter.
• Sound waves are gathered by the outer ear which is shaped to help capture the sound waves ﴾energy transferred in particles of air﴿ and send them through the ear canal, which transfers them to the eardrum.
• The vibrations of air particles cause the eardrum to vibrate.
• If the vibrations follow each other slowly ﴾low frequency﴿ the sound is heard as a low pitch. If the vibrations follow each other in rapid succession ﴾high frequency﴿, the sound
is heard as a high pitch.
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Sound Waves and the Parts of the Ear
• Sound waves with large amplitudes push on the eardrum with more force and are heard as loud sounds. Sound waves with small amplitudes push on the eardrum with less force and are heard as soft sounds.
• Vibrations from the ear drum are transmitted to three small bones of the middle ear, which transmit the vibrations to the inner ear.
• The vibrations in the liquid of the inner ear cause the tiny hairs to vibrate. The vibrating tiny hairs transmit the energy to nerves attached to the hairs.
• The nerve impulses are transmitted to the brain and interpreted as hearing.
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Sound Waves Some sounds are loud. Some sounds are soft. This is called Volume
Intensity ­ Sound with a greater amplitude has a greater intensity.
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Some sounds are high.Some sounds are low. This is called Pitch
Pitch ­ The human perception of the frequency of sound. Sounds with low frequency have a low pitch. Sounds with a high frequency have a high pitch.
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Echoes ­ sounds that reflect off of surfaces. Reverberation ­ repeated echoes. • Echolocation ­ process by locating objects by sounds bouncing off of them.
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Waves of the Electromagnetic Spectrum These are waves that are caused by the interaction of electric and magnetic
fields.
These waves can travel through empty space.
The speed of light in a vacuum is 300 million meters per second. In one year,
light can travel 9.5 trillion kilometers. This is known as a LIGHT YEAR.
The waves are classified according to the wavelength.
The following are the types of waves in the spectrum from longest
wavelength to the shortest. Remember that if the wavelength is long, the
frequency is low!
•
•
•
•
•
•
•
Radio Waves
Microwaves
Infrared Waves
Visible Light
Ultraviolet Rays
X- Rays
Gamma Rays
link to Electromagnetic spectrum
link to Wavelength Order Practice
http://www.youtube.com/watch?v=snNwE6txxP0&feature=related
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Visible Light
Visible light only makes up a small portion of the electromagnetic Spectrum.
• White light is a blend of different colors.
• A white surface reflects all wavelengths to our eyes.
• An object that is black, absorbs all wavelengths.
• An object that is green absorbs all wavelengths except green.
• Red light = longest wavelength.
• violet light= shortest wavelength.
• A prism is a device that can refract (bend) light – each color having its own
wavelength. Yellowish – green is detected best by human eye (can only see
light
between 400 – 700 nanometers).
• Diffraction grating is a material with evenly spaced slits that separate white
light into colors.
• Rainbows are refracted white light created by tiny droplets of water
suspended in the atmosphere.
ROYGBIV
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Parts of ear
Echolocation
Reverberation
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pinna
semi - circular canals
anvil
stirrup
auditory nerve
eardrum
ear canal
cochlea
hammer
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http://www.youtube.com/watch?feature=player_detailpage&v=LyHEHEch8gg
Mr Parr ­ Light
http://www.youtube.com/watch?v=wkl9qAK7MsM&feature=player_detailpage
up close
How eye functions­ seeing the light ­ the eye
vision and perception (30)
Slim Goodbody
http://www.youtube.com/watch?v=gvozcv8pS3c&feature=player_detailpage How we see
http://www.youtube.com/watch?feature=player_detailpage&v=X1hIQvKbQDE ­ Mr Parr ­ light and color
http://www.youtube.com/watch?v=g1KrpsV3­_Y&feature=player_detailpage ­ Near and far sightedness LENS
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Parts of the Eye
Match the part of the eye with the correct function by moving the
correct term next to the function.
retina
iris
Transparent protective covering
pupil
Ring of muscle that contracts and expands
due to changes in light
cornea
Allows light to enter the eye
optic nerve
lens
Convex in shape. It refracts light and forms an
image on the lining of the eyeball. Controlled by
ciliary muscles to help maintain focus
Inner lining of the eyeball that is made up
of millions of cells called rods and cones.
Bonus
Receives signals from the rods and cones and
transmits the image to the brain for
interpretation
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Identify the parts of the eye. Move the word next to the correct position.
cornea
optic nerve
iris
lens
pupil
retina
Correct answers
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How We See an Image
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Convex Lens ­ a lens that is thicker in the center than at the edges. Light rays are bent inward when traveling through this type of lens. The image is similar to an image formed by a concave mirror. The image seen through the lens is inverted and smaller than the object.
Concave Lens­ a lens that is thicker at the edges than in the middle. The light rays are bent outward when traveling through this type of lens. The image is similar to that of a convex mirror. The image is upright and smaller than the object. 43
Types of Lenses
convex
1
3
2
3
2
1
concave
1
2
3
1
2
3
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Farsightedness­cannot see objects that are close clearly. The retina is too close to the eye lens.
convex
focal point
1
3
2
3
2
1
light
Which type of lens will correct this person's eyesight?
concave
1
2
3
1
2
3
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Nearsightedness­ cannot see objects that are far away clearly. The retina is too far from the eye lens.
focal point
light
Which type of lens will correct this person's eyesight?
convex
concave
1
3
2
3
2
1
1
1
2
3
2
3
1
46
Bonus (slide the word to reveal the answer)
What are
cells in the retina that
distinguish among black,
white and gray
and
cells in the retina
that react to color
?
back
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Label the parts of the wave by sliding the name next to the part.
wavelength
Crest
amplitude
trough
back
48
back
49
Identify the parts of the eye. Move the word next to the correct position. Answers
pupil
cornea
retina optic nerve
lens
iris
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Parts of a Wave
Wavelength - the distance between one point on a wave and the nearest point
just like it. The greater the energy carried by the wave, the smaller the
wavelength.
Crest - the top of a wave.
trough - the bottom of a wave.
Frequency - the number of full wavelengths that pass a point each second. The
greater the energy carried by the wave, the greater the frequency.
* Frequency and wavelength are inversely proportional- As frequency increases,
wavelength decreases
Amplitude - the greatest distance that vibrations in a wave move from their
normal position when a wave passes by. The greater the amplitude, the greater
the energy.
Speed - the distance per time that a given wave travels. Waves travel at
different speeds in different mediums. All electromagnetic waves travel at the
same speed in empty space - 300 million m/sec.
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Transmission of Light Answers
Transmission depends on the material.
Opaque - absorbs most of the light. Ex. book, blanket
Translucent - transmits some light. Ex. sunglasses, wax paper
Transparent - nearly all light passes through. Ex. glass, clear water
Move the circle over one of the stars. Then, move the correct term
next to the image shown.
opaque
translucent
transparent
Back
52
Wave Behavior
Refraction - bending of waves caused by change in their speed as they
pass from one medium to another.
Reflection - the bouncing back of a wave when it meets a surface that
does not absorb the entire wave's energy.
Absorption - occurs when the energy is not transfered through the given
medium or space.
Transmission - occurs when waves pass through a given point or medium.
Match the term with the correct illustration
Refraction
Absorption
Reflection
Transmission
Back
53
Place the wavelengths in order from the shortest to the longest
1 3
5
7
2
Microwaves
Gamma Rays
Infrared
Answers
6
4
Ultraviolet
Visible Rays
X­Rays
Radio Waves
Back
54
Place the wavelengths in order from the shortest to the longest
Answers
Gamma Rays
1 Ultraviolet
Infrared
3
Radio Waves
5
7
2
4
X­Rays
Visible Rays
6
Microwaves
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Intensity ­ The amount of energy that a wave carries past a certain area each second. Sound with a greater amplitude has a greater intensity.
Pitch ­ The human perception of the frequency of sound. Sounds with low frequency have a low pitch. Sounds with a high frequency have a high pitch.
Echoes ­ sounds that reflect off of surfaces. Reverberation ­ repeated echoes. Echolocation ­ process by locating objects by sounds bouncing off of them.
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Attachments
j0388289.wav
http.doc
Waves.pptx