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Homework Help: Fermi-sphere derivation

  1. Apr 25, 2010 #1
    1. The problem statement, all variables and given/known data
    use E_m=1/n (E)p(E)dE integral from 0 to Infinity
    to derive E_m=3/5(E_f)


    2. Relevant equations
    n= p(E)dE integral from 0 to infinty
    also n=Q*sqrt(E)dE integarl from 0 to (E_f)
    p(E)=Q*sqrt(E)/(e^(E-E_f)+1)


    3. The attempt at a solution
    i tried doing integration by parts on it and moving stuff around but i cant seem to get it , is there a trick in using that the integral from o to infinty of p(E)dE = 0
     
  2. jcsd
  3. Apr 25, 2010 #2
    Please learn to use the latex command here. Otherwise most people won't understand what you are saying and won't help you. I can't even understand half of what you typed out.
     
  4. Apr 25, 2010 #3
    http://en.wikipedia.org/wiki/Fermi_energy
    scroll about half way down the page and you will see
    total energy of a Fermi sphere , how do i show that , that integral turns into
    3/5(Energy)
     
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