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Homework Help: Elementary charges

  1. Dec 30, 2006 #1
    1. The problem statement, all variables and given/known data
    1) How many electrons make up a charhe of 1 mu C?

    2)What is the magnitude of the force a 10-mu C charge exerts on a 3.0-mC charge 2.0 m away? (1 muC=10^+/-6C , 1 mc=10^+/-3C)

    2. Relevant equations
    FE=(kQQ)/d^2


    3. The attempt at a solution
    1) (10E-6 C)/(1.6E-19)
    I got 6.2E13 but the book says a micro columb is 1.0E-6, and the other book I have says it's 10E-6. Which is it?

    2)FE=[(9.0E9)(1E-4)(0.03)]/4
    =6750 N
    The book says the 10-mu C charge is 10E-6 and the 3.0-mC charge is 3.0E-3.

    I'm confused.
     
  2. jcsd
  3. Dec 30, 2006 #2

    berkeman

    User Avatar

    Staff: Mentor

    I think it's just a limitation of the notation for exponential notation when not using LaTex or some other math typesetting tool.

    A microColoumb is definitely [tex]1*10^{-6} C[/tex]

    And when you try to write exponential notation without using math typesetting, you can try to write it either of the ways you listed.
     
  4. Dec 30, 2006 #3
    That's not right.
    Once you figure out how to make the microcoulomb/millicoulomb conversion, you won't make the same mistake again. Don't mix up microcoulombs (E-6) and millicoulombs (E-3)!

    [tex]10 \mu\rmmath{C} = 10 \times 10^{-6} C[/tex]
    [tex]3 \rmmath{mC} = 3 \times 10^{-3} C[/tex]
     
    Last edited: Dec 30, 2006
  5. Dec 30, 2006 #4
    well if you use scientific notation its gotta be 1.0E-6, cant have anything more than 9 as the base.
     
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