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Is the distance between a trough and crest one wavelength?

  1. Dec 13, 2004 #1
    Is the distance between a trough and crest one wavelength?
  2. jcsd
  3. Dec 13, 2004 #2
    No, 1 wavelength is trough to trough or peak to peak.
    Last edited: Dec 14, 2004
  4. Dec 13, 2004 #3
    It seems that you're thinking about a pure sine wave, in which case the wavelength is the distance between crests (or troughs). But waves are not sine waves in general. If its a complex wave (as many waves in the real world are) then there may be many local crests (or troughs) within one wavelength.

    Last edited: Dec 14, 2004
  5. Dec 13, 2004 #4


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    That would be a HALF wavelength!
  6. Dec 14, 2004 #5
    Yeah I was thinking the samething when I first read it. Its the distance beteen two consecutive crest or troughs.
  7. Dec 14, 2004 #6
    I was thinking this too, but I wasn't sure if a point at the top of a crest was considered in phase with one at the bottom of a trough.

    I've only just been introduced to waves so I have no idea what sine or complex waves are. :redface:
  8. Dec 14, 2004 #7
    Oy vey! Yes. True. How did I miss that? :surprised
    Take a look at this web site. It'll give you an idea.


    Uncheck "red" and "sum" and the result is a sine wave. Now check "red" and it will plot another sine wave on the same axis. Now check "sum" and you'll see the function which is the sum of the two which is a wave, but not a sine wave. Uncheck "blue" and "sum" and you'll see only the sum (the "complex"/"non-simple" wave). See the problem of speaking about troughs and crests?

    Note: By "complex" I don't mean anything to do with complex numbers. I mean "not a simple sine wave."

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