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!

Gauss' Law question

  1. Jun 4, 2013 #1
    1. The problem statement, all variables and given/known data
    a spherical shell has an outer radius R and a inner radius R/2 and carries a total charge -q, distributed with uniform charge density. A point charge +q is at the centre of the sphere. Calculate the electric field strength for R/2<r<R

    2. Relevant equations

    Gauss' Law

    3. The attempt at a solution

    I figured out the charge density in the shell ρ = [itex]\frac{-6q}{7πR^3}[/itex], so the charge enclosed by a gaussian sphere is q(1-[itex]\frac{8r^3}{7R^3}[/itex])

    Then using gauss' law I get E = [itex]\frac{q}{4πε_0r^2}[/itex](1-[itex]\frac{8r^3}{7R^3}[/itex])

    But my book says E = [itex]\frac{q}{4πε_0r^2}[/itex][itex]\frac{8}{7}[/itex](1-[itex]\frac{r^3}{R^3}[/itex])


    Also does anyone know why the latex things aren't working? I'm new to all this stuff.

    Edit: cheers guys
     
    Last edited: Jun 4, 2013
  2. jcsd
  3. Jun 4, 2013 #2

    Don't use the BB code tags like inside the LaTeX code. If you want to do superscripts in the LaTex math code, use ^ .
     
  4. Jun 4, 2013 #3

    Doc Al

    User Avatar

    Staff: Mentor

    Could be that you're combining Latex with non-Latex stuff. Stick to pure Latex and it should work.
     
  5. Jun 4, 2013 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Good.

    Redo that one.

    (FYI: I agree with the book's answer.)
     
  6. Oct 10, 2014 #5
    how do you get
     
  7. Oct 10, 2014 #6

    Doc Al

    User Avatar

    Staff: Mentor

    What's the definition of charge density?
     
  8. Oct 10, 2014 #7
    i dont really understand charge density. all i know is that it have 3 charge densities, volume, area, and linear.
    i just learned this today and i get ρ = −6q/πR3 not ρ = −6q/7πR3.
    can you help me solve this step by step?
     
  9. Oct 10, 2014 #8

    Doc Al

    User Avatar

    Staff: Mentor

    Here we are talking about ρ, which is a volume density.

    Why don't you show how you arrived at your answer?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Gauss' Law question
  1. Gauss's Law Question (Replies: 0)

  2. Gauss's law question (Replies: 9)

Loading...