WAVES
Bellquiz– April 3-4, 2014
1. Draw a transverse wave and label the wavelength and
amplitude.
2. Light waves are (a) ________ and sound waves are
(b)______________. (Answer: longitudinal or transverse)
2. Can light travel in a vacuum (empty space)? (Y/N)
4. Can sound travel in a vacuum (empty space)? (Y/N)
3. Give 2 examples of waves that are transverse waves.
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A. NATURE OF WAVES
Background information
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• Waves – A wave is a disturbance that
transfers energy – it doesn’t transfer matter.
• Medium – Substance or region through
which a wave is transmitted.
• Speed of Waves – Depends on the properties
of the medium, like what state of matter the
medium is.
B. Parts of Waves
1. Wavelength: One complete cycle, ex: crest to
crest OR trough to trough (Units: m, cm, nm, etc)
2. Frequency: The number of cycles (or periods) that
pass in a second (Unit: Hertz, Hz)
3. Amplitude: The distance from the middle to the
top (Units: m, cm, nm)
4. Crest: The highest point of the wave (mountain
crest or peak)
5. Trough: The lowest point of the wave (horses and
pigs eat from a trough - it’s the shape)
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C. Types of waves
1. Transverse waves – energy moves
perpendicular to motion of wave
(Example: Light Waves)
They look like this:
(Now draw one and label the parts)
2. Longitudinal waves – move in and out by
compressing together
(Example: Sound Waves, slinky)
a. Parts
• Compression – close together
• Rarefaction – far apart
Compression
Rarefaction
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Basic wave properties review
– Amplitude – maximum amount of
displacement from the medium at rest; the
height
Amplitude
– Wavelength – the length of one complete
cycle
• Crest to crest OR
• Trough to trough
Wavelength
Light & the Electromagnetic
Spectrum
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LIGHT: What Is It?
• Light Energy
• As atoms absorb energy, electrons jump to a higher
energy level.
• Light is released when the electron falls back down to
the lower energy level.  This is light.
– Photons - bundles/packets of energy released
when the electrons fall.
• Light: Stream of Photons
• This photon travels in a wave.
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What is the speed of
light?
© 2000 Microsoft Clip Gallery
Summary: Light travels at different speeds depending
on the medium. It travels FASTEST in a vacuum, then
gas, then water, then SLOWEST through glass.
Electromagnetic
Spectrum
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Visible Spectrum
• Visible Spectrum – Light we can see
– Roy G. Biv – Acronym for Red, Orange,
Yellow, Green, Blue, Indigo, & Violet.
– Largest wavelength to Smallest
Wavelength.
LIGHT: Refraction
of Light
• Refraction – Bending of light due to a change
in wave speed.
– Prisms – Glass that bends light. Different
wavelengths are bent different amounts & light is
separated into different colors.
R
The ray of light is deviated and
speads out!
Red is deviated least
most / least ?
Violet is deviated most
most / least ?
screen
V
R
There is a spectrum
on the screen:
screen
Red Orange Yellow Green Blue Indigo Violet
ROY G BIV
Roy G. Biv "They Might be Giants"
V
What to do now?
screen
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V