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Homework Help: Down to the Wire

  1. Feb 28, 2008 #1
    A current of I=8.0\;\rm A is flowing in a typical extension cord of length L=3.00 m. The cord is made of copper wire with diameter d=1.5mm.

    The charge of the electron is e=1.6 *10^{-19} C. The resistivity of copper is \rho=1.7 *10^{-8}\; Omega*m. The concentration of free electrons in copper is n=8.5 *10^{28}\;m^{-3}.

    Find the total number of collisions ( N_c) that all free electrons in this extension cord undergo in one second.

    I know Velocity(drift) = 3.3 * 10^-4 m/s.

    I tried to relate the formula V_d = a*Tau, to find Tau the time between collisions...

    However given the information I was stuck solving for a = eE/M_e, because I could not determine the electric field...

    Can someone please assist me on what information I might be missing?
  2. jcsd
  3. Feb 29, 2008 #2
  4. Mar 5, 2008 #3
    im still stuck on this question...
  5. Mar 6, 2008 #4
    ok so since no one seems to have a clue about this problem...

    any suggestions of where I may be able to find the answer?
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