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Homework Help: Intensity of sound and finding distance from sound source

  1. Oct 19, 2011 #1
    The intensity of the sound from a certain source is measured at two points along a line from the source. The points are separated by 11.8 m, the sound level is 68.10 dB at the first point and 60.31 dB at the second point. How far is the source from the first point?

    I = P/A = Ps/(4*pi*r^2)
    SL = 10log(I/Io)

    Io = 1*10^-12 W/m^2

    Using these equations I found both I(1) and I(2) which turned out to be I(1) = 6.46 * 10^-6 and I(2) = 1.07 * 10^-6. Each of these equal P/(4*pi*r^2) except for I(2), r = r1+d where d=11.8m. I put I(1)/I(2) which canceled out P and made it [(r1+1.8)^2]/(r1^2). When I expand and solve, the answer I get is incorrect. Am I missing some detail for solving this problem?
  2. jcsd
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