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Homework Help: Derivative of Planck's spectral distribution

  1. Feb 26, 2017 #1
    1. The problem statement, all variables and given/known data
    From differentiating Planck's distribution and setting it equal to 0 I've reached the equation below. But now I'm asked to estimate the solution for a/λ. It's suggested that we try to do it graphically/trial and error as it's tricky to do analytically.

    I'm wondering how I would go about doing it graphically; I feel like I'm missing something...

    Any help would be appreciated, many thanks

    2. Relevant equations
    http://www.sciweavers.org/upload/Tex2Img_1488126559/render.png [Broken]

    a = hc/KbT

    3. The attempt at a solution

    I did try rearranging to get it in the form:

    http://www.sciweavers.org/upload/Tex2Img_1488126973/render.png [Broken], But again I'm unsure how I can obtain something useful (graphically I mean)
    Last edited by a moderator: May 8, 2017
  2. jcsd
  3. Feb 26, 2017 #2


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    What about looking at the intersection of a line and an exponential?
    Last edited by a moderator: May 8, 2017
  4. Feb 26, 2017 #3
    Ohhh.... I see. Thank you
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