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Homework Help: Calculating dB with I

  1. Sep 14, 2009 #1
    1. The problem statement, all variables and given/known data

    Calculate the sound level in decibels of a sound wave that has an intensity of 4.00u "W/m2.

    2. Relevant equations

    dB = 10log(I/Io)

    3. The attempt at a solution

    dB = 10log(4/1E-12) = 126.02 db

    Book says 66db. It vaguely covers this topic, not sure if I had missed something or not.
  2. jcsd
  3. Sep 14, 2009 #2


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    Homework Helper

    That's 4.00 micro-watts per meter squared, or 4.00 * 10^-6 W/m^2. It isn't 4 W/m^2..
  4. Sep 14, 2009 #3

    pft... I completely overlooked that. Its getting late!
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