1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electron drift speed in a copper wire.

  1. Apr 8, 2007 #1
    I'm really stuck on this one problem:

    "A small but measurable current of 4.20E-10 A exists in a copper wire whose diameter is 0.02 cm. Calculate the electron drift speed (in meters/second)."
    Source: Serway and Jewett

    I know that:
    I = 4.20E-10 A
    n = 8960 kg/m^3
    q = 1.6E-19 C
    d = 2E-4 m

    J = (I/A) = n x q x v
    Thus, v = I/(n x q x A)

    What does A stand for and how would I go about finding it? Also, am I converting things correctly and using the proper value for the density?

    Any help would be greatly appreciated.
  2. jcsd
  3. Apr 8, 2007 #2
    A is the cross-sectional area of the wire.
  4. Apr 8, 2007 #3
    Thank you for the hint. I found the answer now. Apparently I was getting the n density the wrong way as well.

    Proper way to find n: :smile:

    For the copper wire in the problem:
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook