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

Displacement current density

  1. Jan 27, 2010 #1
    Hi, just to check which equation for Jd (the displacement current density) is correct:

    1) Jd = ε0εr(dE/dt), or
    2) Jd = ε0(εr-1)(dE/dt)

    1) came from the fact that Jd = ε(dE/dt) and ε=ε0εr
    2) came from differentiating P = ε0(εr-1)E (since Jd=dP/dt).

    It's only a minor thing but in a question I'm doing, it gives a different answer to 1 s.f. so you can't really just say that εr = εr-1.

  2. jcsd
  3. Jan 27, 2010 #2


    User Avatar
    Science Advisor

    The first equation is correct. The displacement current has two sources.
    One is dE/dt, and one is dP/dt, which add to each other. Your second equation is only for the dP/dt part.
  4. Jan 27, 2010 #3
    Ah ok, thanks a lot =)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Displacement current density
  1. Displacement Current (Replies: 1)

  2. Displacement Current (Replies: 2)