1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Average wavelength for blackbody radiation

  1. Aug 21, 2010 #1
    The maximum wavelength for blackboby radiation is .29/Temperature. Is the average wavelenght 1.84 times the maximum for all temperatures?
  2. jcsd
  3. Aug 21, 2010 #2
  4. Aug 21, 2010 #3
    As shown in both ref., the wavelength where the emission intensity is maximum is .29/T. But I want to know the avg wavelenght at that temperatue. So I think the wavelenght where the area under the intensity ghaph is equal on both sides would be the average, but I do not know how to calculate it from gragh equation. My estimate working back from other calculations was 1.84 times the max wavelenght.
  5. Aug 21, 2010 #4
    You can calculate the following:

    Use Planck's Law for the blackbody radiation power as a function of T and λ


    u(T,λ) = [2hc25]/[e(hc/λkT) - 1]

    The average wavelength is then given by:

    λavg = ∫λ u(T,λ) dλ / ∫ u(T,λ) dλ

    where both integrals are from 0 to ∞. The appendix of the above wiki solves the important integrals.

    Bob S
  6. Aug 21, 2010 #5
    Do you know if the average is 1.84 the maximum for all temperatures? I can not do the math. The following quote from the source may relate: This function peaks for hc = 4.97λkT, a factor of 1.76 shorter in wavelength (higher in frequency) than the frequency peak. Thanks jimj
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Average wavelength for blackbody radiation
  1. Blackbody radiation? (Replies: 1)

  2. Blackbody radiation (Replies: 6)