Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Calculating resistivity from relaxation time.

  1. Aug 15, 2011 #1
    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.
  2. jcsd
  3. Aug 15, 2011 #2

    Dr Transport

    User Avatar
    Science Advisor
    Gold Member

    the formula for the conductivity [itex]\sigma[/itex] is given by

    [itex]\sigma = \frac{ne^2 \tau}{m}[/itex] where [itex] n [/itex] is the density, [itex] e [/itex] is the electrical charge, [itex] \tau [/itex] is the relaxation time and [itex] m [/itex] mass of the electron. From here you should be able to find the resistivity.
  4. Aug 16, 2011 #3
    i did the calculation, i got: 1.6e-3 Ohmm is that correct, or am i missing something.
    thanks for quick reply
  5. Aug 16, 2011 #4
    If we used the same metal (copper) in hall probe to measure the magnetic field, how can i calculate the hall coeficient of copper and the magnetic field acting on copper.

    thickness 100um
    hall voltage 0.1uV
    current 1.5 A
  6. Aug 16, 2011 #5
    i am a bit confused, is there a reason why the molar mass isn't in the equation?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook