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: Determining current and drift speed

  1. Mar 5, 2008 #1
    [SOLVED] Determining current and drift speed

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

    http://img162.imageshack.us/img162/145/problemrg5.jpg [Broken]

    The two wires in the above figure are made of the same material. What are the current and the electron drift speed in the 2.0mm-diameter segment of the wire.

    2. Relevant equations

    I = J/A; J = n*e*v_d where n is the density of the conductor in m^-3 and v_d is drift velocity.

    3. The attempt at a solution

    I was able to find the density of the conductor:

    [tex]n = \frac{I_{1}}{(Aev_{d_1})} = 2*10^{28}[/tex]

    Also, I reached to this relationship between [tex]I_2[/tex] and [tex]v_{d_2}[/tex]:

    [tex]I_{2} = 20000v_{d_2}[/tex]

    What to do next? Appreciate any pointers, and thanks in advance.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Mar 6, 2008 #2
    Ah, again, I_2 = I_1. *smacks head* This solves the problem.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook