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!

Electric field 0.1mm above charged plate.

  1. Sep 19, 2009 #1
    1. The problem statement, all variables and given/known data
    A thin 0.08x0.08 meter copper plate is charged with 9*10^9 electrons. What are the strength and direction of the electric field 0.1mm above center of the top surface of the plate.


    2. Relevant equations
    n=Q/A
    E=n/E_0


    3. The attempt at a solution\
    I found the linear charge density to be 2.25*10^-7 c/m^3 from the first equation above. I multiplied the number of electrons by the charge of a single electron and divided by the area.

    Next I took the linear charge density and divided it by epsilon_0 to get a final charge of 25423.72 N/C.
    I plugged this into webassign but it says thats wrong? could someone check this for me because I swear this is the right way to go about this problem
    thanks
     
  2. jcsd
  3. Sep 19, 2009 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    That equation is for a pair of oppositely-charged plates.

    For a single plate, it's

    E = n/2εo

    They might want you to watch the number of significant figures in the answer you report, too.

    Other than that, things look okay to me.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook