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Homework Help: Conversion units mystery. Am I wrong?

  1. Apr 6, 2013 #1
    1. The problem statement, all variables and given/known data
    The potential difference between two points is 140mV. If 280μJ of work are required to move a charge Q from one point to the other, what is Q?

    2. Relevant equations
    Q = W/V

    3. The attempt at a solution
  2. jcsd
  3. Apr 6, 2013 #2


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    Homework Helper

    Hi, welcome to PF!

    Convert the potential difference to volts, and the work to joules. Dividing joules with volts, you get coulombs for the charge. mJ/mV is also coulomb.

  4. Apr 6, 2013 #3
    You are assuming that mJ divided by mV gives mC. That's wrong, it gives C. In general, you have overcomplicated things too much. Just convert everything into J and C, compute the result, then convert it to any units you want.
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