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: Which way does the electric field go in this question?

  1. Jun 21, 2014 #1
    1. The problem statement, all variables and given/known data

    Find the electric field midway between a -3.0nC charge and a -5.0 nC charge that are separated by 0.60 m.

    2. Relevant equations

    ε= kq/r2

    3. The attempt at a solution

    net ε = ε1 + 2

    I drew my -3.0 charge on the left and my -5.0 charge on the right

    midway in between is 0.3 m

    they are both negative charges, so the fields lines are towards each charge (away from the centre) and the -5.0 charge has more lines, because it has the bigger charge

    so I solved for ε 1 and got -300 N/C
    I solved for ε 2 and got -500 N/C

    I think that ε 1 should be subtracted from ε 2 so the result is

    -200 N/C

    The field overall, I think should point toward the larger negative charge

    it should point toward the -5.0 nC charge, in my drawing, to the RIGHT.

    is that correct?

    Last edited: Jun 21, 2014
  2. jcsd
  3. Jun 21, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Yes, the field at the midpoint, points toward the -5.0 nC charge.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted