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: Electric Force Equilibrium

  1. Sep 6, 2012 #1
    1. The problem statement, all variables and given/known data
    Two identical conducting small spheres are placed with their centers .300 m apart. One is given a charge of 12.0 nC and the other is given a charge of -18.0nC. a) Find the electric foce exterted on one sphere by the other. B) the sphers are connected by a conducing wire. Find the electric force between the two after they have come to equilibrium.

    2. Relevant equations
    F=(((q1)(q2))/r^2)(8.99 x 10^9 N M^2/c^2)

    3. The attempt at a solution
    I used the above equation to calculate the charge to be -2.1576 x 10^5 N. for problem A. For B, I am curious if i'm simplyfying to much, but since there is equilibrium would the resulting charge be zero?

    Thank you for the help!
  2. jcsd
  3. Sep 6, 2012 #2
    The resultant charge is the sum of the original charges. What is it?
  4. Sep 6, 2012 #3
    -6.0 nC because there is still a disproportionate number of electrons within the system? Is it found by adding the two forces together?
    Last edited: Sep 6, 2012
  5. Sep 6, 2012 #4
    It's -6.0 nC because one sphere had +12 and the other had -18. The total charge of the system must be conserved.

    You need to figure out how this charge is divided between the two spheres, though.
  6. Sep 6, 2012 #5
    Is it an even -3.0nC charge in each sphere because the spheres and the connecting wire are both conductive so the electrons are equally spaced?

    Then using the -3.0nC in the original formula as both q1 and q2 to calculate the new repulsive force?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook