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Homework Help: Calculating electric field strength

  1. Mar 15, 2010 #1
    1. The problem statement, all variables and given/known data

    http://img219.imageshack.us/img219/3310/problemi.png [Broken]

    2. Relevant equations

    F = kq/r^2

    3. The attempt at a solution

    O ----- x ----O -----------O

    Let the electric field of the first O be E1, second be E2, third be E3.
    RED - .02m
    BLUE - .016m
    GREEN - .033m

    E1 = (9 * 10^9) (7.6 * 10^-6) / (.02^2) = 1.70763 * 10^8
    E2 = (9 * 10^9) (1.6 * 10^-6) / (.016^2) = 5.61722 * 10^7
    E3 = (9 * 10^9) (2.8 * 10^-6) / (.033 + .016)^2 = 1.04811 * 10^7

    E1 and E3 are going -> and E2 is going <-.
    So I figured the magnitude of the electric field strength would be the absolute value of E1 + E3 - E2 which turned out to be 1.25072 * 10^8 N/C.

    However the answer is apparently wrong and I'm not sure where I made a mistake =\.
    Any help is appreciated.

    Never mind I caught my mistake after re-reading what I typed out...turns out I used 7.6 for the first charge instead of 7.9 :(
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
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