(adsbygoogle = window.adsbygoogle || []).push({}); 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

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

**Physics Forums | Science Articles, Homework Help, Discussion**