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Finding maximum in Planck's law

  1. Sep 11, 2010 #1
    1. The problem statement, all variables and given/known data
    At what wavelength is u(lambda) a maximum for a star with a surface temperature of 50,000 K?

    2. Relevant equations
    Planck's law

    3. The attempt at a solution
    I think the maximum is where the derivative of the function u(lambda)=0, but the derivative is too messy to solve in terms of lambda so I can't find the wavelength. So I think I'm way off as far as how to solve it. Any help would be appreciated.
  2. jcsd
  3. Sep 12, 2010 #2
    well, the differentiation should be done in order to get \lambda at maximum energy density. The differentiation isn't too hard, try using the product rule first.
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