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

Magnetic experiment

  1. Feb 28, 2004 #1
    Hi all
    a few days ago a friend of mine show my this experiment, that i cant explain

    he took a rectangular ceramic magnet dim 2" x 2" x 1" and put on a table with north polarity up, next he took a coin shape neodymium magnet with nort polarity down and begin to approach to the big . In the begining , there is a repulsion , but with a little push the coin magnet can be attached to the big

    how is it possible, not we were saying, opposites atract and similars repel?
     
  2. jcsd
  3. Feb 28, 2004 #2

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The magnetic fields caused by magnets shaped that way are not as simple as the basic bar magnet field you're used to seeing. I'd bet the magnets stuck together a little off-center, right?

    - Warren
     
  4. Feb 29, 2004 #3
    not only that

    and to finish my tale, i'll tell you that when you have the two magnets stucked, if you approach slowly a third magnet of similar power than ceramic, the coin magnet is released to a distance of at least 0.5 feets, like a catapult. Very interesting
     
  5. Mar 1, 2004 #4

    turin

    User Avatar
    Homework Helper

    How sure are you that the poles were axial? I had some AlNiCo disk magnets that had poles on the edge of the disk rather than one face N and the other S. Of course, that is not what I wanted, but I only found out about it when I saw how they stuck together.
     
  6. Mar 1, 2004 #5
    try it

    the coin magnet can only be attached to a little region in the center of the ceramic magnet with dimension similar to the coin. Outside this region the magnet is strongly repeled and is impossible to do that.

    why dont try it?Its easy to replicate

    thks
     
  7. Mar 1, 2004 #6

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Two different people have already told you what is happening, no one is doubting what you are seeing. The poles are not the two faces of the plate but the the center and the edge. turn your plate magnet over. What happens now? Should be the same as the other side. Flip you "coin" magnet over? What happens?

    Try approaching the edge of the magnet with your "coin", what happens?
     
  8. Mar 1, 2004 #7
    turn magnet

    when i turn big magnet the "coin" is attracted hardly over all the surface INCLUDING the edge. Does it agree with your idea?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?