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!

Electric Forces HELP!

  1. Jan 29, 2005 #1
    Ok,

    the problem states: there are four charges, each with a magnitude of 2.0 uC. Two are positive and two are negative. The charges are fixed to the corners of a 0.30 m square, one to a corner, in such a way that the net force on any charge is directed toward the center of the square. Find the magnitude of the net electrostatic force experienced by any charge.

    Anyway. I think that it is like this + -

    + -

    So since the only attraction I see is : one positive to two negs, one across and one diagonal, no vertical but repulsive force.

    So I do my components... Fx=kQq/r^2 = 8.99x10^9 (2.0x10^-6C)(2.0x10^-6C)/(0.30^2) = 0.3995 N. Since I got my x component and my y, essentially same, I do pythagoras and get the answer 0.56497 N for the net force.

    Ideas?

    Thanks!
     
  2. jcsd
  3. Jan 29, 2005 #2
    There are three forces acting on each charge. Your answer gives the magnitude after accounting only for the two nearby attractive charges. But you need to also include the repulsive charge which is across the diagonal.
     
  4. Jan 29, 2005 #3
    diagonal? wouldnt' that be a attractive force?
     
  5. Jan 29, 2005 #4
    So there are three forces one across, one diagonal and one vertical (repulsion). The repulsion force is the same as the horizontal attraction, which is F= 0.3995 N. The diagonal force, is 0.200N found by finding the length of the diagonal line. So to find the net charge, I have to break down the 0.200 N into it's components right? I get approx. F=0.141 N for both x and y components. I add up the forces. For Fx= 0.3995+0.141 N= .5405N. And the Fy=0.3995-0.141 N = 0.2585 N. Use pythagoras and get Square Root of (0.3589)= 0.5990 N?
     
  6. Jan 29, 2005 #5

    Doc Al

    User Avatar

    Staff: Mentor

    Note that this implies that the charges are arranged so that like charges face each other across a diagonal, like this:
    + -
    - +
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Electric Forces HELP!
  1. Electric Force Help! (Replies: 13)

Loading...