Today 1/16

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Today 1/16

• Waves
• Interference of Waves
• HW 1/16 HW Handout Superposition Due Wed,
  1/22 (beginning of class)
• Read Ch 16.1,2,5 Ch 17.1,2
• Suggest Problems 16-1,2,3,4,5,8
• Note This lecture is mostly animations and is
  more than 80 slides long! Beware the print button!

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Things to think about
Consider a traveling wave sound, light, football
stadium, water...
How would you define a wavelength?
How would you define a frequency?
How would you define a wave velocity?
How does the direction of the waves motion
compare to the direction of the individual
particles motion?
What happens when two waves run into each other?
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How does the direction of the waves motion
compare to the direction of the individual
particles motion?
Wave moves right while particles move up and
down.Called a transverse wave
Examples are light, water, and football stadium,
sound is a longitudinal wave.
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Wavelength (?) ?
? 8 units
Wave Velocity (v) ?
Direction is to the right, v ?x/?t
?x is ? and ?t is T, the time for a particle to
go through one complete oscillation, as in SHM.
v ?/T
Frequency, f 1/T also as in SHM.
v ?f
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What happens when two waves collide?
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waves just meeting
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?
?
?
Superposition!!!
Green wave says move up but blue wave says move
down so...
Particle does not move!!
Superposition means superimpose all effects at
a chosen location then add them up (as vectors)
to get the net effect at that location.
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Now lets put this in motion.
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
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Destructive interference
Constructive interference
This is a standing wave and is a
superposition of two traveling waves. These
two waves interfere with each other causing
locations of constructive and destructive
interference.
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Destructive interference
Constructive interference
Note that the locations of constructive and
destructive interference alternate. These
locations are called nodes (destructive) and
anti-nodes (constructive).
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Your first Homework...