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: What does divergence of electric field = 0 mean?

  1. Apr 3, 2016 #1
    1. The problem statement, all variables and given/known data
    I just want to focus on the divergence outside the cylinder (r >R)

    2. Relevant equations

    3. The attempt at a solution
    For r > R, I said ∇ * E = p/ε

    But that's wrong. The answer is ∇ * E = 0

    I'm confused because there is definitely an electric field outside the cylinder (r > R). The electric field points radially outwards and gets smaller the farther you get from the cylinder because

    So I don't understand how the divergence of the electric field can be 0. I think the main part of my confusion is that I don't understand what the divergence is. I know how to mathematically compute the divergence but I don't understand it physically. Like when the divergence of the electric field is 0, what does that mean in terms of the physical electric field?
  2. jcsd
  3. Apr 3, 2016 #2


    User Avatar
    Homework Helper
    Gold Member
    2017 Award

    Gauss' law says that the divergence of E evaluated at some point equals the charge density at that same point divided by ##\epsilon_0##.

    These videos might help improve your conceptual understanding of divergence:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted