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Electricity - Charges

  1. Jun 23, 2008 #1
    1. The problem statement, all variables and given/known data
    If an electroscope has a positive charge of 7.5 x 10[tex]^{-11}[/tex]C, how many electrons have been removed from the electroscope, if it was originally neutral?

    (Answer: 4.7 x 10[tex]^{8}[/tex])


    2. Relevant equations
    I don't know :shy:


    3. The attempt at a solution
    Guys I seriously am clueless with this question. I understand basic electricity a little, like circuits, but I don't even know where to start with this. I have all formulas required, but I don't know which one to use, and my exam is tomorrow :uhh:

    There are also some other questions which I'll probably post later, I'm really stuck on this, and your help is appreciated... a lot!

    Thanks
     
  2. jcsd
  3. Jun 23, 2008 #2

    Redbelly98

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    What is the charge of a single electron?
     
  4. Jun 23, 2008 #3
    -1?? I don't know to be honest with you.
     
  5. Jun 23, 2008 #4

    rock.freak667

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    an electron has a charge of [itex]-1.6 \times 10^{-19}[/itex]
     
  6. Jun 23, 2008 #5
    Okay, thanks.. but how do I put that into the question??
     
  7. Jun 23, 2008 #6

    rock.freak667

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    The charge on the scope= Ne
    where N=No of electons and e=charge on one electron
     
  8. Jun 23, 2008 #7
    well... what you told me is like a completely new language to me... thanks for the help, but i really don't understand it (i understand what you're saying but i don't know what to do with that)... is there a specific equation i can use?

    EDIT: I'm going to bed, my exam's early in the morning... I guess electricity won't be that great on the exam. Thanks everyone for the help.
     
    Last edited: Jun 23, 2008
  9. Jun 24, 2008 #8

    Redbelly98

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    It might have been beneficial to include units (Coulombs) in that answer, but anyway it's a moot point now.
     
  10. Jun 24, 2008 #9
    Well I did the exam today so i'm done with physics for now... no need for the answer... I think I did pretty decent on the exam... no questions like that, though.

    Thanks everyone for the help.
     
  11. Jun 24, 2008 #10
    well...at least everything well
     
  12. Jun 24, 2008 #11

    rock.freak667

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    Even though it's up to you to want to know the answer, IMO it's best to understand how to get the answer so in case you are presented with a similar question,you'd know how to get through it.
     
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