Intensity and Wattage

  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. Simon Bridge

    Simon Bridge 14,649
    Science Advisor
    Homework Helper
    Gold Member

    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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