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

Does a magnet wear out?

  1. Dec 22, 2006 #1
    I was surprised not to find a question about this from before, but the question is simply; does a "normal" refrigerator magnet wear out? Will it eventually loose its power and fall to the floor...?
     
  2. jcsd
  3. Dec 22, 2006 #2

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Yes, it will.
     
  4. Dec 22, 2006 #3
    Only quantized magnetization is permanent.
     
  5. Dec 22, 2006 #4

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    What does that mean? What's "quantized magnetization"?
     
  6. Dec 22, 2006 #5

    Chronos

    User Avatar
    Science Advisor
    Gold Member
    2015 Award

    'Wear' is a somewhat misleading term. Permanent magnets gradually decrease in strength, but this has very little to do with usage. The "life" of a permanent magnet depends on many factors. Naturally occuring forces conspire to knock the little domains out of alignment. But this is normally a very slow process. Temperature is a major player in this process. The higher the temperature, the faster this process will occur. Extreme heat [surpassing the curie point] will immediately randomize the domains. A sharp blow can also knock domains out of alignments, as can other nearby magnetic or electrical fields. Radiation can also knock domains out of alignment. But again, under normal conditions, neither your fridge or you will live long enough to watch the little fellow fall to the floor in exhaustion. At the quantum leve [e.g., electrons] magnetism is eternal.
     
  7. Dec 23, 2006 #6
    Gokul43201,

    By "quantized magnetization" I mean properties like the magnetic moments of the electron, muon, proton or neutron, and perhaps surface magnetic field quantum effects near a superconducting ring with Josephson junction.
     
  8. Dec 23, 2006 #7

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    In that case, you should make it clear what you mean, because the terminology you used is, by no means, typically applied to these cases. Magnetization is a statistically defined quantity - it is a property of an ensemble of particles, not the property of a single particle. You can talk of the magnetic moment of an electron, but not of the magnetization of an electron!
     
  9. Dec 23, 2006 #8
    Thank you, I will endeavor to remember that.
     
  10. Dec 31, 2006 #9
    godd answer chronos.
    But for generality, the fact that the fridge magnet is on the fridge (steel door). This will act in the same way as a keeper. Hence it will maintain its magnetism for a substantial length of time. More than if it was just resting on a table for instance. Of course, the domain theory will dictate its eventual downfall.
     
  11. Dec 31, 2006 #10
    sorry I meant good not godd!!!!!!!!!!!
     
  12. Dec 31, 2006 #11
    Was that a misnomer?
     
  13. Jan 1, 2007 #12
    :rofl: :rofl: :biggrin:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Does a magnet wear out?
Loading...