Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Derivation of Electric Field with Gauss's Law

  1. Nov 14, 2015 #1
    I did everything I could to solve the following problem:
    A solid ball of radius rb has a uniform charge density ρ.

    What is the magnitude of the electric field E(r) at a distance r>rb from the center of the ball?
    E(r) =

    My third attempt went like this: qencl=[ρ(4/3)(π)rb3]

    EV=[ρ(4/3)(π)rb3]/(ε0)
    E(4/3)πr3=[ρ(4/3)(π)rb3]/(ε0)

    And ah, well, a little simple division and cancelling leads to:
    [ρrb3/[ε0r3]

    However, the book answer is 1/3 my answer. Could someone please tell me where this constant develops?
     
  2. jcsd
  3. Nov 14, 2015 #2
    Try Gauss's law. Start by writing the equation for Gauss's law.
     
  4. Nov 14, 2015 #3

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    The righthand side is okay. Check the details on the lefthand side of this equation.
     
  5. Nov 14, 2015 #4
    Why did you multiply the electric field with the volume?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Derivation of Electric Field with Gauss's Law
Loading...