Waves

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Waves
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Waves

• Carry information energy over distance
• Types of waves
• Sound
• Radio
• Microwave
• Recognizing waves
• Vibrations sound light etc.

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• Waves spread through connections
• Moves along a string because the string is
  continuous
• Types of waves
• Transverse oscillations perpendicular to the
  direction the wave moves
• Up/down water waves
• Longitudinal wave oscillations in the same
  direction as wave moves

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Example of Longitudinal Wave
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Wave Parts

• Frequency measure of how often it goes up and
  down
• Measured in hertz (Hz)
• Amplitude largest amount that goes above or
  below
• Wavelength length of one complete cycle of a
  wave distance from point on one wave to same
  point on next wave
• Represented by ? (lambda) upside down y

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• Speed describes how fast the wave can transmit
  an oscillation from one place to another
• Speeddistance wavelength x frequency
• time
• v f?
• v speed (m/s) f frequency (Hz)
  ? wavelength (m)

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Sample Problem 1

• A wave with a frequency of 14 Hz has a wavelength
  of 3 meters.  With what speed will this wave
  travel? 
• First, we identify the variables in our problem
  wavelength 3 meters frequency 14 Hz
• We place the variables in their correct position
  in the speed formula Speed wavelength x
  frequency Speed 3 meters x 14 Hz
• Perform the calculation and express the resulting
  speed value with the appropriate unit Speed
  42 m/sec

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Sample Problem 2

• The speed of a wave is 65 m/sec.  If the
  wavelength of the wave is 0.8 meters, what is the
  frequency of the wave?
• First we identify the information given in the
  problem Speed 65 m/sec wavelength 0.8
  meters
• Place the variables in their correct position in
  the speed formula Speed wavelength x frequency
  65 m/sec 0.8 meters x frequency
• Solve the problem to find the frequency value
  frequency 81.25 Hz

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Practice Problems

• A wave has a frequency of 46 Hz and a wavelength
  of 1.7 meters.  What is the speed of this wave?
• A wave traveling at 230 m/sec has a wavelength of
  2.1 meters.  What is the frequency of this wave?
• Answers 78.2 m/s and 109.5 Hz

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Practice Problems

• A wave with a frequency of 3.1 Hz and a
  wavelength of 0.2 meters experiences a
  lengthening of wavelength to 1.4 meters.  What is
  the new frequency of this wave?
• Answer 0.44 Hz

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Waves in Motion

• Crest (wave fronts) highest point
• Trough lowest point
• Shape of the crest determine the direction the
  wave moves

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Wave Interactions

• Reflection wave bounces off and goes in a new
  direction
• Water waves traveling toward a wall
• Refraction wave can pass straight into and
  through the obstacle
• Diffraction wave can bend around or through
  holes in the obstacle
• Can hear someone even though a door is only
  slightly open
• Absorption wave can be absorbed and disappear
• Theaters curtains absorb sound waves

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Reflection
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Refraction
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Diffraction
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• Waves
• Define waves and how they relate to energy.
• Define the following properties of waves
  frequency, wavelength, amplitude, crest, and
  trough.
• Identify the following properties of waves
  frequency, wavelength, amplitude crest, and
  trough.
• Describe the relationship between frequency and
  wavelength.
• Calculate the speed of a wave using the
  equation v f x l
• Distinguish between transverse and longitudinal
  waves.
• Explain how transverse and longitudinal waves
  differ.
• Explain how transverse and longitudinal waves are
  similar.
• Explain the difference between reflection and
  diffraction

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Slinky Lab