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Homework Help: Basic Electricity

  1. Sep 17, 2006 #1
    Hey everyone,

    There is a question in my book that asks if three particles touch and are then seperated (A- +5q, B - -q, C - 0) what is the net charge? I know the answer is 4q, but it also states the following:

    Particle C touches A and is removed. Particle C then touches B and is removed. What is the final charge on C? I got 1.333... but the answer in the back of the book says 1.5. Am I doing something wrong?
  2. jcsd
  3. Sep 17, 2006 #2


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    Staff Emeritus
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    If you could explain how you got 1.33... we could help find where you went wrong.
  4. Sep 17, 2006 #3
    i did net charge 4q / 3
  5. Sep 17, 2006 #4


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    Staff: Mentor

    The question is a little ambiguous. You are correct if the first thing you do is touch them all together, as in your question #1. However, the book's answer is correct if you start again in question #2 with the balls having their initial (different) charge states. Do the problem again with that assumption, and you'll get the correct answer.
  6. Sep 17, 2006 #5
    ok. It works like that. I wonder why they didn't word it correctly. It's worded to do it how I did the first time...

    Anyways, thanks for your help!
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