1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

Help with understanding electromagnetic induction

  1. Jul 17, 2010 #1
    When a charge is in motion, it produces a magnetic field. If the charge is in an external magnetic field, a magnetic force is induced on the charge. This I understand.

    When a conductor is moving relative to a magnetic field, there is an induced current in the conductor. This I don't get. If the conductor is stationary, and the magnet is moved around it, then how is there a magnetic force exerted on the electrons in the conductor to induce a current? Wouldn't the conductor need its own magnetic field for a magnetic force to be exerted on it, and for it to have a magnetic field wouldn't it have to be in motion?

    Thanks in advance.
  2. jcsd
  3. Jul 17, 2010 #2
    It doesn't have to be magnetic force to induce current. If the magnet is moved, the field it creates is no longer a static magnetic field; it's electromagnetic field instead. The E-component of the field exerts forces on the electrons of the conductor.
  4. Jul 17, 2010 #3
    I don't get it.
  5. Jul 17, 2010 #4
    Where do you not get it?
  6. Jul 17, 2010 #5
    The entirety of what you said.
  7. Jul 17, 2010 #6
  8. Jul 18, 2010 #7
    Take a look at the illustration of an aviation ignition magneto on page 3 of this article by Will Fox:

    http://eaa691.org/files/Tech Note #2 Magnetos.pdf

    The rotating 4-pole magnet induces an alternating magnetic field in the iron core, which generates a voltage and current in the coil (primary = 180 turns). This is a battery-less ignition system, where the power is generated by the rotating permanent magnet. This works on the Faraday law of induction.

    Bob S
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook