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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
    http://imgur.com/FDaQfb9
     
  2. jcsd
  3. Apr 6, 2013 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    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.

    ehild
     
  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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