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Homework Help: Intensity and Wattage

  1. Dec 1, 2011 #1
    1. The problem statement, all variables and given/known data
    OK, so this is a very basic question but i am uncertain what the relationship is. I know its logarithmic, but i don't know how to draw a conclusion. Here is the question:
    If you want an amplifier which will give a sound output which is twice as lod as your present 20 W amplifier, what amplifier power should you buy? What if you wanted a sound output four times as loud?

    2. Relevant equations

    3. The attempt at a solution
    I know that the relationship between Intensity and Wattage is logarithmic, but how do i draw a numeric conclusion?
  2. jcsd
  3. Dec 1, 2011 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    Are they looking for loudness or intensity?

    The wattage of the amplifier is the maximum power it can supply to the signal.
    The intensity a wave is the square of it's amplitude.
    I suspect you are thinking of decibels.

    If you double the amplitude, you get four times the intensity.
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