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Resistor Nyquist-Johnson noise formula question

  1. May 2, 2010 #1
    Hi all -- I had a question about the Nyquist-Johnson noise formula:

    [itex]
    \[
    E_{\nu}^{2}d\nu=\frac{4R_{\nu}hd\nu}{e^{h\nu/kT}-1}\]
    [/itex]

    which of course can be approximated for most purposes as [itex]$ E_{\nu}^{2}d\nu=4R_{\nu}kTd\nu$[/itex].

    I'm just wondering why the formula has [itex]$ exp(h\nu/kT)-1$[/itex] in the denominator? I would have expected [itex]$ exp(h\nu/kT)+1$[/itex] as electrons are fermions, so obey Fermi-Dirac statistics as opposed to Bose-Einstein. Sure I'm missing something obvious!

    Cheers
     
  2. jcsd
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