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Homework Help: Interference of waves

  1. Jan 25, 2010 #1
    1. The problem statement, all variables and given/known data
    Two audio speakers are facing each other, as shown in the picture:
    https://online-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys214/spring10/hwb/01/05/speakers.gif [Broken]

    The speakers emit sound at 1300 Hz; initially the speakers emit in phase (φB = 0). Assume the speed of sound is 330 m/s. A special microphone that is in the middle, i.e, equidistant from the speakers, responds to the net sound intensity from the speakers. If only the left speaker (A) is on, the microphone registers an intensity IA = 2 Watts/m2. If only the right speaker (B) is on, the microphone registers an intensity IB = 4 Watts/m2.

    Now we turn down the right speaker, so that both speakers individually produce intensity IA = IB = 2 Watts/m2. Also, assume the frequency is still 1200 Hz, and φB = 0. How far would you have to move the microphone toward speaker B to have a minimum in intensity?

    2. Relevant equations

    3. The attempt at a solution

    I think sketching Imic(x), the net intensity as a function of distance from the original (central) location would help me a lot here to solve this. But as having the phase as 'zero', i have no idea how to proceed further..

    Please could someone help me out here?
    Last edited by a moderator: May 4, 2017
  2. jcsd
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