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Homework Help: Electric Force charge magnitude

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

    A 1.0-C charge is 15 m from a second charge, and the force between them is 1.0 N.
    What is the magnitude of the second charge?

    2. Relevant equations

    F = k(q1)(q2)/r^2

    3. The attempt at a solution

    F = k(q1)(q2)/r^2 need to solve for q2 so...

    F(r^2)/k(q1) = q2

    1N(225m)/(9x10^9)(1C) = 25nC

    That is correct, right? I just wasn't sure because this is on my sample exam, but we never used nano numbers during class so I wanted to double check.
  2. jcsd
  3. Feb 27, 2010 #2
    though i didn't actually calculate it, your setup looks right. nC is a common measure of charge.
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