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Homework Help: Intensity of sound

  1. May 23, 2010 #1
    1. The problem statement, all variables and given/known data

    By what factor is the intensity of sound at a rock concert louder than that of a whisper when the two intensity levels are 120 dB and 20 dB respectively?

    2. Relevant equations

    The sound level of a sound wave in decibles is

    [tex]\beta = 10 log (\frac{I}{I_0})[/tex]

    Also the ratio of intensities:

    [tex]\beta_B - \beta_A = 10 log (\frac{I_B}{I_A})[/tex]

    3. The attempt at a solution

    Using the latter equation:

    [tex]100 = 10 log (\frac{I_B}{I_A})[/tex]

    Solving for the ratio I get 22026.4. Now how can I determine the factor one intensity is greater than the other? I'm not quite sure... :confused:
  2. jcsd
  3. May 23, 2010 #2


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    Homework Helper

    The equation should be

    [tex]100 = 10log_{10}(\frac{I_A}{I_B})[/tex]

    Or [tex]10 = log_{10}(\frac{I_A}{I_B})[/tex]

    Now find the ratio of the intensities.
    Last edited: May 23, 2010
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