1. Not finding help here? Sign up for a free 30min 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!

Where along line is electric field zero?

  1. Jan 24, 2009 #1
    1. The problem statement, all variables and given/known data
    Two charges of +4microC and +9microC are 30cm apart. Where on the line joining the charges is the electric field zero?


    2. Relevant equations
    Ep=E1+E2=0
    E1=Kq1/x^2
    E2=Kq2/(r-x)^2

    3. The attempt at a solution
    Since charges are alike, put Ep=E1-E2=0, then E1=E2
    Substituted for E1 and E2
    eventually leads to q1(r^2-2rx+x^2)=q2x^2

    He told us to use quadratic since it's more secure, but that requires the (r^2-2rx+x^2) to be set equal to zero, which i cannot figure out how to do
     
  2. jcsd
  3. Jan 24, 2009 #2

    LowlyPion

    User Avatar
    Homework Helper

    The way I look at it you get something like:

    4/x2 = 9/y2

    Taking the square root of both sides yields

    2/x = 3/y

    That looks a little easier to deal with doesn't it?
     
  4. Jan 24, 2009 #3
    Never mind, i got it. I plugged in the values for q1 and q2, distributed, subtracted the right from left, then used quadratic. Thanks for your help anyway!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Where along line is electric field zero?
Loading...