1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted