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

Types of dipoles and their fields

  1. Oct 16, 2015 #1
    Hi guys! Sorry for all the questions on electromagnetism. My understanding is that an electric field exists in electric monopoles and dipoles, as well as moving magnetic dipoles, and magnetic fields only exist in magnetic dipoles and moving electric dipoles. Is this correct? There are 2 parts of that that I am not sure about: Is there an electric field in a non-moving magnetic dipole, and is there a magnetic field in a moving electric monopole? Thanks in advance!
     
  2. jcsd
  3. Oct 16, 2015 #2

    Dale

    Staff: Mentor

    No. You have to have a changing dipole.

    Yes. This is described by the Lienard Wiechert potentials.
     
  4. Oct 16, 2015 #3
    There is a problem in the way you stated it. The fields don't exist "in" the dipoles, etc., but are generated by, and exist all round them, in empty space. A moving magnetic dipole generates an electric field in the following way. The moving magnetic dipole changes the magnetic field at any given point in space, and the changing magnetic field generates an electric field according to Maxwell's equations. Whether a stationary magnetic dipole generates an electric field depends on how the magnetic dipole is structured. For example, a rotating charge is a magnetic dipole, and it generates both a magnetic field and an electric field. An electric monopole is just a point charge, and a moving point charge does generate a magnetic field.
     
  5. Oct 16, 2015 #4
    Thank you.
     
  6. Oct 16, 2015 #5
    Ok, and jut to make sure, the difference between a magnetic and electric dipole is if there is any distance between the 2 poles. Correct?
     
  7. Oct 16, 2015 #6

    Dale

    Staff: Mentor

    No. Magnetic dipoles are formed by small loops of current. Electric dipoles are formed by positive and negative charges separated by a small distance.
     
  8. Oct 16, 2015 #7
    Then how can a 2-sided magnet be a magnetic dipole?
     
  9. Oct 16, 2015 #8
    Ok. I see what I got wrong. What is really misleading me are the pictures of current loops. They all draw the same field lines, however some sources say that the field lines show the magnetic potential, and some say the field lines are showing the magnetic field.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Types of dipoles and their fields
  1. Electric Dipole Field (Replies: 1)

Loading...