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!

How much stored energy do the plates have?

  1. Mar 4, 2017 #1
    1. The problem statement, all variables and given/known data
    Two parallel circular plates with radius 7.0 mm carrying equal magnitude surface charge of Q = 4.618 x 10-10 C are separated by a distance of d = 1.0 mm (0.001 m). How much stored energy do the plates have?

    2. Relevant equations
    Acircle = π r2
    C = ∈0⋅A / d
    PE = 1/2 ⋅ Q2 / C
    PE = 1/2 ⋅ [(Q2⋅d) / (∈0⋅A)]
    0 = 8.85 x 10^-12

    3. The attempt at a solution

    Area = π ⋅ (0.007)2
    Area = 1.539 x 10-2 m2

    PE = 1/2 ⋅ [((4.618x10-10)2⋅0.001) / (8.85x10-12 ⋅1.539 x 10-4)]
    PE = 7.829 x 10-8 J

    PE ≈ 78 nJ
    (is this correct?)
     
    Last edited: Mar 4, 2017
  2. jcsd
  3. Mar 4, 2017 #2

    gneill

    User Avatar

    Staff: Mentor

    Other than using the variable C for energy your result looks good. :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted