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Homework Help: Coulomb's law

  1. Nov 19, 2013 #1
    Hi, Can someone help me with this question? I understand Coulomb's law but i want to know if I am doing it right.
    So the charge of
    Q1= 2 mC
    Q2= 1 mC
    And R= 5 cm (0,05m)
    This is how i solved it.
    F= K(8,988x10^9) x (2x10^-6)x(1x10^-6) / (0,05m)^2
    F= K(8,988x10^9) x 8x10^-10
    F= 7.1904 N

    Is 7.1904 the right answer?
  2. jcsd
  3. Nov 19, 2013 #2
    Hi Tony Tesla...

    Welcome to PF!!

    1mC = 10-3C , not 10-6C

    Please recheck your calculations.
  4. Nov 19, 2013 #3
    Submultiples Multiples
    Value Symbol Name Value Symbol Name
    10−1 C dC decicoulomb 101 C daC decacoulomb
    10−2 C cC centicoulomb 102 C hC hectocoulomb
    10−3 C mC millicoulomb 103 C kC kilocoulomb
    10−6 C µC microcoulomb 106 C MC megacoulomb
    10−9 C nC nanocoulomb 109 C GC gigacoulomb
    10−12 C pC picocoulomb 1012 C TC teracoulomb
    10−15 C fC femtocoulomb 1015 C PC petacoulomb
    10−18 C aC attocoulomb 1018 C EC exacoulomb
    10−21 C zC zeptocoulomb 1021 C ZC zettacoulomb
    10−24 C yC yoctocoulomb 1024 C YC yottacoulomb
    Common multiples are in bold face.

    Source: http://en.wikipedia.org/wiki/Coulomb

    I think it is 10^-6

    Now i see it i typed Mc instead of μC
  5. Nov 19, 2013 #4
    I see now, I ment μC not mC sorry.
  6. Nov 19, 2013 #5
    Even then your calculations are wrong.

  7. Nov 19, 2013 #6
    checked it 5 timed every time the answer was 7.1904 N
    After that i went to this page: http://www.endmemo.com/physics/coulomb.php
    and the answer there was also 7.1904 N
  8. Nov 19, 2013 #7


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    Homework Helper

    The solution for the force is correct if the charges are given in μC .

  9. Nov 19, 2013 #8
    Thank you
  10. Nov 19, 2013 #9
    Yes...your solution is correct.I misread the given data.
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