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Homework Help: Relaxation time = displacement lifetime of fermi sphere?

  1. Apr 20, 2007 #1


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    1. The problem statement, all variables and given/known data

    I just want to clear this up, im a little confused:

    when an electric field is applied there is a force on the electron K-states thus displacing the fermi surface/sphere

    Is the relaxation time ([tex] \tau[/tex])= lifetime of fermi sphere displacement

    or is lifetime of displacement= reciprocal relaxation time

    both are labebel as [tex]\tau[/tex] in my notes and related as below but how can they be the same?

    2. Relevant equations

    [tex] \sigma = \frac{n e^2 \tau}{m}[/tex] electrical conductivity

    [tex] \rho = \frac{1}{\sigma}=\frac{m}{n e^2 \tau}[/tex] electrical resistivity
    Last edited: Apr 20, 2007
  2. jcsd
  3. Aug 15, 2011 #2
    Given the following data on copper, how do i calculate the resistivity?

    Relaxation time: 2.50e10-14s
    Density: 8940Kgm-3
    molar mass: 63.5g

    is there an equation for it.
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