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

Energy in Magnetic Field

  1. Jun 26, 2004 #1
    I am curious about is there any energy can be found / get in the magnetic field?
  2. jcsd
  3. Jun 27, 2004 #2
    Yes: in classical electrodynamics, a magnetic field in vacuum has an energy density of u0B2. This energy can be extracted. For example, a conductor moving at an angle through a magnetic field develops a potential difference between its endpoints. This can be used to run a current, thus performing work. The energy for that could only have come from the field, and indeed the resulting assembly produces a magnetic field that partially cancels the original field, maintaining energy conservation.
  4. Jun 27, 2004 #3
    Then where is the energy come from?
  5. Jun 27, 2004 #4
  6. Dec 10, 2004 #5
    Uh...you of course meant to say energy density is B2/2u0, right zefram?

    Creator :wink:
  7. Dec 10, 2004 #6
    Indeed that's what I meant. Can't everyone take a nap in class every now and then?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook