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!

Homework Help: Pressure on charged spherical shell, alternative solution

  1. Jun 6, 2012 #1
    1. The problem statement, all variables and given/known data
    Find the pressure on a uniformly charged spherical conducting shell of Radius R and total charge Q. The answer is (Q^2) / (32*π*ε*R^4)

    I´m fine doing this using the derivative of the energy as the sphere grows to get the force.

    My question is: Why do I get twice the answer if I think of a small surface element dA and calculate the force on it as the field E = Q/(4πεR^2) multiplied by the charge on that surface element, dQ = dA*(Q/(4πR^2) ?

    I cannot see where I double the force. How should this approach be mended?

    Thanks for reading this,

  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