Waves

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2/22/06 Waves The Wave Equation CH 15, 33
neat application, but not really waves. Leave
till end Thursday Computer Exercise 2, meet
in Olin 269 (Astro Lab) Friday Chap. 16 Sec.
16-1 thru 16-5
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Particles vs. Waves
Types of Waves
Transverse vs. Longitudinal
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ConcepTest 29 A string is held at one end,
while the other end goes over a pulley and is
attached to a mass M, as shown. Transverse waves
on the string travel with speed v. If the mass
M is quadrupled, what is the new wave speed?
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ConcepTest 30 Two wave machines are hooked
together. The wave machine on the left has a
wave speed higher than the wave machine on the
right. Consider the following choices

• A wave pulse comes from the left to the right
  (high speed region to low speed region). Which
  of the above is correct for the REFLECTED pulse?
• b) A wave pulse comes from the left to the right
  (high speed region to low speed region). Which
  of the above is correct for the TRANSMITTED pulse?

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Wave traveling from one medium into another
Wave Speed cares about Medium
Speed changes
Example Light Speed in vacuum c Speed in
medium v Index of refraction n gt 1 ? larger
n, slower speed

• Incident waves splits up into
• Reflected wave
• Transmitted wave

High speed ? Low speed Reflected Wave INVERTED
Low speed ? High speed Reflected Wave NOT
INVERTED
Video Demos
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Mathematical Description of Waves the Wave
Equation
Partial Derivatives
Dont panic
? Wave function describes oscillation about
equilibrium
Wave functions?
Examples position of slinky coil pressure
of air (sound wave) electric field (EM wave)
Examples
Wave Equation
Concentrate on Harmonic Waves
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Harmonic Waves
snapshot
Fixed position
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Definitions
snapshot
Fixed position
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ConcepTest 31
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ConcepTest 32

• What is the amplitude of this wave?
• What is the wavelength of this wave?
• What is the angular frequency of this wave?
• What is the speed of this wave?