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Homework Help: The determination of frequency v from Planck's formula

  1. Mar 11, 2008 #1
    1. The problem statement, all variables and given/known data
    B=10^-7Wm^-2Hz^-1sr^-1;T=10^4K
    h=6.6x10^-34J.s
    k=1.4x10-23JK^-1
    c=3.0x10^8m^-1

    2. Relevant equations

    Calculate v fom Bv(T)=(2hv^3)/(c^2)x1/(exp(hv/kT)-1)



    3. The attempt at a solution
    I have managed to obtain a LHS= (Bc^2/2h)xexp(h/kT)
    but RHS is posing a problem to me!
    I just cannot resolve v^3/(exp v-1)
    I have tried the tactic of changing the base of the exp to log10 throughout but I am still left with v^3/((log v/log 2.718) - .4342) on the RHS to deal with!
    I should expect an answer v = 10^15 Hz but the best I get is ~10^18

    Thanks I hope I have made this clear as I'm not particularly computer literate
     
  2. jcsd
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