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Homework Help: Power Output

  1. Dec 2, 2007 #1
    1. The problem statement, all variables and given/known data

    The Sun emits electromagnetic waves (including light) equally in all directions. The intensity of the waves at the Earth's upper atmosphere is 1.4 kW/m2. At what rate does the Sun emit electromagnetic waves? (In other words, what is the power output?)
    ____ W

    2. Relevant equations


    3. The attempt at a solution

    I have no idea how to do this one....

    I know it involves I = P/A
  2. jcsd
  3. Dec 5, 2007 #2

    Shooting Star

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    Homework Helper

    If r is the dist of earth from sun, then total energy W emitted by sun in one second will fall on the surface of a sphere of radius r in one second (after 8.3 mins or so).

    W/(4*pi*r^2) = 1.4*10^3 (given). You have to plug in the value of r in meters. That's all.
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