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Homework Help: Find the intensity of a sound - Wave problem

  1. Aug 19, 2007 #1
    1. The problem statement, all variables and given/known data
    A small source of sound radiates energy equally in all directions. At a particular frequency, the
    intensity of the sound 1.0 m from the source is 1.0 x 10-5m Wm-2, corresponding to an amplitude of oscillation of air molecules of 70milimetre. (Assume no energy loss)
    Find (i) the intensity of the sound

    2. Relevant equations
    Energy is proportional to the square of the amplitude by a point
    Intensity is proportional to the inverse of the square of the radius
    Intensity is proportional to the square of the amplitude

    3. The attempt at a solution
    (A)^2 proportional to (1/(r^2))
    A proportional to (1/r)
    And since the amplitude is 70 * 10^-3
    I tried using this way to solve the above question. But I have doubts as hm..mathematically its wrong somewhere. Is there another way to do this question?
  2. jcsd
  3. Aug 19, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    I don't understand the question. You are given the intensity at one distance, but what are you being asked to find? (You may have left out part of the question.)
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