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 at the point within the sheet

  1. Apr 20, 2009 #1
    1. The problem statement, all variables and given/known data

    A huge (effectively infinite) horizontal nonconducting (epsilon = epsilon_0) sheet 10 cm thick has charge over both faces. The upper face carries a uniform +95 nC/m^2 while the lower face carries a uniform -25.0 nC/m^2. The magnitude of the electric field at a point within the sheet 2.00 cm below the upper face is closest to :

    2. Relevant equations

    E= k q/r^2

    3. The attempt at a solution

    Etotal = E1 + E2

    E1 = k q1 / r^2 = 9 * 10^9 * 95 *10^-9 / (0.02)^2 = 2137500

    E2 = k q2 / r^2 = 9 * 10^9 * 25 *10^-9 / (0.08)^2 = 35156.25

    Etotal = E1+E2 = 2172656.25 N/C

    is this correct or not?
    Thanks
     
  2. jcsd
  3. Apr 20, 2009 #2

    dx

    User Avatar
    Homework Helper
    Gold Member

    Your formula for E is for point charges. For an infinite sheet of charge with surface charge density σ, E is σ/2ε. You can prove this using Gauss' law.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook