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Homework Help: Electric potential distance problem?

  1. May 19, 2006 #1
    Hi everyone I need very badly some help with this problem please:

    A force of 0.053 N is required to move a charge of 39 µC a distance of 30 cm in an electric field. What is the size of the electric potential difference between the two points?

    Is the electric potential difference the force divided by q (whatever that is) divided by distance? That's what someone told me. I can't find q though. Is that even the right way to to it?

    I'm not really sure how to do this at all. I tried to do it for more than an hour yesterday but my teacher is TERRIBLE and I don't get it. The book doesn't really help either. Can someone solve it and guide me through it?

    Thanks a whole lot!
  2. jcsd
  3. May 19, 2006 #2


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    Homework Helper

    There are a few relationships involving voltage (or potential difference) V. The one you need here is [tex]W = QV[/tex] where V is the potential difference, Q is the charge and W is work done. W is the work required to move a charge Q against a potential difference of V.

    Now, use another relationship that you should know between work, force and distance to form an equation and solve for V.
  4. May 20, 2006 #3
    You should probably like to know the actual meaning of voltage. I personally like sentences.

    Voltage is the potential energy difference, per unit charge.
  5. May 20, 2006 #4


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    Homework Helper

    Sorry, sorry, sorry. I misread xXPhoenixFireXx's post. I missed the word "energy" in it, I thought he said "potential difference per unit charge" (which would be wrong). My apologies. I've deleted my post.
    Last edited: May 20, 2006
  6. May 20, 2006 #5
    haha hate it when that happens. I may as well delete mine as well 'cause I don't want to detract from the the purpose of the thread.
  7. May 20, 2006 #6
    Okay thanks.

    So exactly is q though? I'm confused. Is it 32 in the problem above or do I need to solve for it? If so what equation do I use?
  8. May 20, 2006 #7
    The charge Q is the 39 micro Coulombs that was given in the question
  9. May 20, 2006 #8
    Thanks. Do I need to conver it?
  10. May 20, 2006 #9


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    Yes, you should convert it to Coulombs.

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