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!

Find charge density rho of a uniform shpere with radius R

  1. Feb 21, 2015 #1
    1. The problem statement, all variables and given/known data
    Find the potential V(r) inside and outside of a uniformly charged sphere with radius R and total charge q.
    A) Fix first the charge density ρ(r) in the two regions 1: r>R and 2: 0<r<R the results should only be in terms of q and R


    2. Relevant equations
    ρ= qtot/Vtot
    dq= ρ*Venc

    3. The attempt at a solution
    ρ= qtot/(4/3)piR^3
    dq = [(qtot/(4/3)piR^3)*(4/3)pir^3]dr⇒(q*r^3/R^3)
    ∫dq = ∫q*(r^3/R^3)dr⇒ q*(¼r^4/R^3)

    not sure if this is the correct approach to the problem
     
  2. jcsd
  3. Feb 22, 2015 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Don't forget brackets: ρ= qtot/((4/3)piR^3) or ##\rho = \frac{3q}{4\pi R^3}##. Also, is this the charge density everywhere?
    I don't understand what you are trying to do in the two lines below. You found the charge density, what does the integral mean and why do you integrate over a charge?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted