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: Find the electric field a distance z from the centre of spherical

  1. Nov 30, 2011 #1
    1. The problem statement, all variables and given/known data

    Find the electric field a distance z from the centre of spherical sphere of radius R which carries uniform density B. treat Z<R (inside) and Z>R (outside)………. By using law of cosine how to solve this problem?

    2. Relevant equations

    1/4∏εo∫ (σ da/ r^2) cos(theta)
    3. The attempt at a solution
    substituting r by law of cosin.. r=√R^2+z^2-2Rzcos(theta)
    1/4∏εo ∫[σ da/ R^2+z^2-2Rzcos(theta)]cos(theta)
    i am stuck here what should i do next

    Attached Files:

  2. jcsd
  3. Nov 30, 2011 #2
    Re: electrodynamics

    Is the charge density given by a surface density, or a volume density? When talking about a sphere and not a spherical shell, one ought to remember that the inside is filled(in this case with charge).
    In any case,
    Try the following:
    dA = rdr\sin(\theta)d\theta d\phi
    dV = r^2dr\sin(\theta)d\theta d\phi
    Phi goes from 0 to 2pi,
    Theta goes from 0 to Pi.
    r from zero to R.
    Try it,
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook