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

Homework Help: Calculating drift velocity of electrons in a conductor

  1. Apr 2, 2012 #1
    1. The problem statement, all variables and given/known data

    Calculate the drift velocity of the elctrons in a conductor that has a cross-sectional area of 8x10^-6m^2 and carries a current of 8A. Take the concentration of free electrons to be 5x10^28 electrons/m^3 with 1.6x10^-19C charge on each electron.

    2. Relevant equations



    3. The attempt at a solution

    Have a problem like this one on my study guide. Wanted to see how it was done in steps.
     
  2. jcsd
  3. Apr 3, 2012 #2
    The amount of charge passing a point in the wire in time t:
    Q = NqvtA

    N = electron concentration
    q = electron charge
    v = drift velocity
    t = time
    A = cross-sectional area

    So:
    v = Q/(NqtA)

    But current is:
    i = Q/t
    so substitute this in:

    v = i/(NqA)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook