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Homework Help: Calculating current given the current density and area

  1. Mar 20, 2015 #1
    Hello, I am having trouble getting the correct solution to the following problem, even though I think my steps all are correct!! What did I do wrong?

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

    2. Relevant equations
    Current = current density * area
    Current = charge/time So, time = charge / current

    3. The attempt at a solution
    For the first part I get: [tex]Current = 6.67\cdot10^6 A/m^2 * 1.41\cdot10^{-3} =9404.7A[/tex]
    For the second part I get: [tex]time=\frac{4.77*10^{20} electrons \cdot 1.602\cdot10^{-19} C/electron}{9404.7A}=0.00813s[/tex]

    And as I stated, I'm not getting the correct answer. As you can see my units all match up. Do you see a math error? Or have I misunderstood a concept.

    Thank you,
  2. jcsd
  3. Mar 20, 2015 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Yes. Check your units one more time.
  4. Mar 21, 2015 #3
    Thank you, know I know 1mm^2=10^-6 m^2
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