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Homework Help: Calculation of urrent

  1. Jun 27, 2010 #1
    1. The problem statement, all variables and given/known data

    Imagine a point A on a piece of conducting material. If r electrons flow to the right of A and l ions flow to the left, what is the current at A?

    2. Relevant equations

    3. The attempt at a solution

    No idea! Please help!
  2. jcsd
  3. Jun 27, 2010 #2
    Do you mean that r electrons flow to the right of A and l ions flow to the left per time unit? What is the charge of the ion?
    Last edited: Jun 27, 2010
  4. Jun 27, 2010 #3
    Yes, per unit time.

    Let's assume that the charge of the ion is twice the charge on the electron.
  5. Jun 27, 2010 #4
    Current is the flow rate of positive charge.
    In case of negative charge, current flows opposite to the flow of charge.

    Handle each charge separately.

    If I ions flow past A per unit time, how much charge has flown past A per unit time?
    That gives you the current due to I.

    Do the same for the electrons, this time current would flow opposite to their flow.

    Then, add up the currents due to the ions and the electrons to get the total current.
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