1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Frequencies of standing wave in pipe

  1. Apr 13, 2013 #1
    1. The problem statement, all variables and given/known data

    A speaker is placed near the open end of a 0.5m pipe (closed on the other end).
    what is the speed of sound if the pipe resonances at 600Hz for n=2?



    2. Relevant equations

    fn=(2n+1)*V/4L
    Or?
    fn=(2n-1)*V/4L

    3. The attempt at a solution

    I saw both versions of the formulas above, which one is correct?
     
  2. jcsd
  3. Apr 13, 2013 #2

    TSny

    User Avatar
    Homework Helper
    Gold Member

    Both formulas are correct. The first one assumes that the possible values of n are 0, 1, 2, 3, .... The second formula assumes the values of n are 1, 2, 3, .... So both formulas will produce the same set of resonant frequencies.

    However, since the formulas produce a different frequency for the same n, you would need to know which formula the problem wants you to use. It's probably the same formula that was used in class or in your textbook.
     
  4. Apr 13, 2013 #3
    Thanks for the clarification!
     
  5. Apr 13, 2013 #4

    cepheid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Well, the bottom version of the formula obviously doesn't work for n = 0, whereas the top one does, so I'm assuming the two versions are just dependent on where you start counting from. They both generate identical harmonics if you let n be 0, 1, 2, 3, ... for the top one and 1, 2, 3, ... for the bottom one.

    EDIT: I was sitting there too long with my compose window open while doing something else and got beaten to the punch!
     
  6. Apr 13, 2013 #5
    Thanks anyway cepheid.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Frequencies of standing wave in pipe
Loading...