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Homework Help: Sound Waves and Destructive Interference question

  1. Apr 29, 2008 #1
    The problem:
    Two speakers emit a sound with a frequency of 550.0Hz. At what distance should they be placed to maximize destructive interference?

    I have the steps in solving this problem written on my worksheet, and it says that the speakers should be placed at 1/2 wavelength. The thing I don't understand is WHY they should be placed there. Other than that, I understand how to finish solving the problem. I just don't understand what the deal is with 1/2 wavelength.

    Thank you!
  2. jcsd
  3. Apr 29, 2008 #2


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    Homework Helper
    Gold Member

    You want the sound waves (assumed to be in phase) to destructively interfere? What does this mean in terms of two waves overlapping? i.e. What part of wave 2 must overlap with a crest on wave 1 to cause destructive interference?

    You should see (if you draw the waves coming from each speaker to scale) that this overlap will happen if the two speakers are half a wavelength apart.
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