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Homework Help: Compressions and rarefactions of a sound wave

  1. Oct 17, 2008 #1
    1. The problem statement, all variables and given/known data
    Well it's not so much a direct question as it is several.
    I'm very confused about sound waves. I know that, when modelled as a transverse wave on a set of axis, a compression is a maximum and a rarefaction is a minimum. But where do nodes and antinodes fit into this? Which is a node, which is an antinode?
    What's more, I'm even more confused about actual loud points. Are compressions and rarefactions considered to be loud points, meaning the point in the middle is a quiet point?

    3. The attempt at a solution
    See attached image.
    You can see that I had a go at labelling the wave myself. Could someone please replace my labels with the correct ones?
    Thanks very much.

    Attached Files:

  2. jcsd
  3. Oct 20, 2008 #2


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    Staff Emeritus
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    Well, what are the definitions of a node/antinode?

    What's plotted on the y axis of this graph?
  4. Oct 20, 2008 #3
    I'm not sure about the definitions! Therein lies the problem :D

    Well, it depends how you interpret it. It's got the X axis, which could be seen as 0. On a Voltage vs. time graph, both maximums and minimums are 'high' points of voltage, so this could be the same.
    On the other hand, the notion of a minimum suggests it's very little sound, and I was sure rarefactions were quiet points, being the absence of particles, but it's hard to visualize.
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