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 Field Strength problem.

  1. Dec 13, 2011 #1
    1. The problem statement, all variables and given/known data
    2 point charges are situated 45nm apart in a vacuum. Charge A is +8μC and charge B is -25μC. X is a point 8nm from A.

    Calculate the electric field strength at point X only due to A (Ans is 1.2 x 10^9 N/C)
    Calculate the overall electric field strength at point X due to A and B. (Ans is 1.32 x 10^9 N/C)

    2. Relevant equations
    E = [itex]\frac{1}{4\pi\epsilon}[/itex] X [itex]\frac{Q}{d^{2}}[/itex]


    3. The attempt at a solution
    Electric field strength due to A.
    [itex]\frac{1}{4\pi(8.9X10^-12)}[/itex] X [itex]\frac{8X10^-6}{(8X10^-9)^{2}}[/itex]

    = 1.117X10^21
    = 1.12X10^21 N/C


    Electric Field Strength due to B.
    E = [itex]\frac{1}{4\pi(8.9X10^-12)}[/itex] X [itex]\frac{25X10^-6}{(37X10^9)^{2}}[/itex]

    = 1.632X10^20
    = 1.63X10^20 N/C




    1.12X10^21 + 1.63X0^20 = 1.283X10^21 N/C


    Where am I going wrong?
    I would appreciate any help.
     
  2. jcsd
  3. Dec 13, 2011 #2

    gneill

    User Avatar

    Staff: Mentor

    It doesn't look like you've done anything wrong. The "answers" given seem to be well out of whack in terms of order of magnitude.
     
  4. Dec 13, 2011 #3
    I don't see anything wrong with a and b either but the combined field is a vector sum and one of the charges is negative and the other, positive.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Electric Field Strength problem.
Loading...