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Homework Help: What are the resonant wavelengths?

  1. Jun 22, 2010 #1
    1. The problem statement, all variables and given/known data
    Consider pipe of lenght L. The pipe is closed at one end and open at the other allowing a standing wave where a node exists at the closed end and a max exists at the open end.
    a) what are the resonant wavelengths?
    b) If L=5, what is the lowest frequency?


    2. Relevant equations
    f= c/L where c=speed of light, L=pipe length, f=frequency


    3. The attempt at a solution

    I think I got it right, I'm just looking for some confirmation and any other insight you may have for me.

    a) L since it says the pipe length is L, it can't go any longer then that.

    b) f=C/ L = 3*10^8/5= 0.6*10^8 Hz=60 Mega Hz
     
  2. jcsd
  3. Jun 22, 2010 #2
    Are you guys studying sound waves in pipes? If so, you dont need c, you need the speed of sound in air... Also did you discuss pipe lengths and how the nodes and antinodes produced by inteference cause resonance in the pipes if they are the proper length? You perhaps discussed tuning forks vibrating air in a pipe of some length? Anything familiar in what I have written?
     
    Last edited: Jun 22, 2010
  4. Jun 22, 2010 #3
    We are just touching on basics of different waves, sound included. Yes we did touch a little on the nodes. No, we did not discuss tuning forks in a pipe.
     
  5. Jun 22, 2010 #4
    Did you discuss the difference between closed at one end and open and both end pipes and sound? Because if you did not, its not easy to make sense of what you need to put in for L, the length of the pipe.
     
  6. Jun 22, 2010 #5
    This might help. Read resonance of a air in a tube... I doubt you guys are using the end correction part... There are some nice diagrams that display the standing waves produced along with the nodes and antinodes in both types of tubes.

    http://en.wikipedia.org/wiki/Acoustic_resonance

    Im off for fishing...
     
  7. Jun 22, 2010 #6
    I don't believe we did, but if you say that it wouldn't make sense if we didn't, then why would we be assigned this question? And it says that L=5 in part b.
     
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