Review Equation Sheet for Final Exam Class Homepages

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Review Equation Sheet for Final ExamClass
Homepages
Standing Waves Flaming Tube o Fire Sound waves
are just pressure/displacement waves in a
material. They are longitudinal. Closed tube
ends must be displacement nodes. Open tube ends
must be pressure nodes. -gt Standing wave
resonances, harmonics.
Power in waves
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If the intensity of a (bright) light bulb is 4
W/m2 at a distance of 1 m, by what factor is the
intensity reduced at 2 m?
B
C
By what factor is the peak electric field reduced
at 2 m, compared to 1m?
A smaller by a factor of eight (one eighth as
large) B smaller by a factor of four (one fourth
as large) C smaller by a factor of two (one half
as large) D smaller by a factor of v2 E
unchanged
The intensity of a periodic surface ocean wave
originating from a volcano right at the surface
is 4 W/m at a distance of 10 km. By what factor
is the intensity of that wave reduced at a
distance of 20 km?
C
By what factor is the peak amplitude of the ocean
wave reduced?
D
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Interference

• The addition of two or more waves is called
  interference. So standing waves can be thought of
  as a reflected wave interfering with an incident
  wave.
• (Its really a misnomer, the waves go right
  through each other!)
• In 2D or 3D, you can also have interference. It
  is especially interesting when you have two
  sources. Points that are a half wavelength
  farther from one source than the other will get
  almost no sound!
• wiki

http//bugman123.com/Physics/Interference.gif