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: Capacitance homework

  1. Jan 13, 2010 #1
    1. The problem statement, all variables and given/known data

    If the electric field is E and

    div.ξ=ρ/ϵ_0


    where
    ξ=-dV/dx


    show that the capacitance is
    C=(ϵ_0 A)/d


    because i dont know how to type it i'm representing ξ with E for the electric field



    3. The attempt at a solution

    I've done this as two two bits

    if E=-dV/dx i've said E=v/d

    and div.ξ=ρ/ϵ_0

    dE/dx=ρ/ϵ_0

    E=(sigma)/ϵ_0 (integral) dirac function

    E=sigma/ϵ_0

    sigma/ϵ_0 =Q/Aϵ_0

    Q/Aϵ_0=V/d

    C=Aϵ_0/d

    i'm wondering if i've got this right, sorry if its hard to follow
     
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted