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Homework Help: A problem about standing waves

  1. Dec 1, 2011 #1
    1. The problem statement, all variables and given/known data
    Why it is the antinode at the open end?

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 1, 2011 #2

    PeterO

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    Homework Helper

    For the standing wave in an organ pipe, displacement nodes correspond with pressure anti-nodes, and displacemment antinodes correspond with pressure nodes.

    If you have an antinode at an open end, you must be referring to a displacement antinode [because that is what you get there].

    That means a pressure node.

    Pressure wise - at an open end, there is no reason for the gas to build up pressure, as it is unconfined.
    Displacement wise: being an open end, the gas particles can move in and out at will, so maximum movement is possible → an antinode.

    This applet should clarify:
    Read carefully, notice which way the particles move and when the particles are crowded together or not.

    http://www.walter-fendt.de/ph14e/stlwaves.htm
     
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