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

Materials that effect fields from Perminant magnets?

  1. Apr 10, 2006 #1
    hi all, Please can you help list materials that can be used to Block, Reduce, Stabilize, Increase or react with the fields from perminant magnets

    il start with

    Graphite: A Magnetic Stabilizer
    Coper: A Magnetic Inductor
  2. jcsd
  3. Apr 11, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    Materials in what way?

    Do you mean materials added to ferromagnetic materials/alloys or surrounding them or juxtaposed?
  4. Apr 12, 2006 #3
    i mean externaly,Materials that can interact with the field

    for example a material that would block the magnetic field from the perminant magnet if you surrounded the maget with it.

    another example would be how graphite sheets will stabilize a perminant magnets field in such a way as to allow it to levitate.

    copper will induce electric charge when disrupted by magnets.

    any examples like that would be of great interest
    Last edited: Apr 12, 2006
  5. Apr 16, 2006 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The magnetic field from a permanent magnet is just that - a magnetic field, it is no different from the magnetic field produced from an electromagnet. The last three words in your sentence are hence redundant.

    This is a misleading description - to say, without elaboration, that graphite is a "magnetic stabilizer". There is no material property known as magnetic stability. Graphite is a moderate diamagnet. When used in the right geometry, it provides a shallow potential well for a magnetically levitated object (again, only in a specific geometry), which results is better stability against mechanical perturbations.

    Second, it is meaningless to say that copper is a "magnetic inductor". Inductance is a geometrical property, not a material property. Copper is essentially non-magnetic**. The reason copper is used in transformer windings is because of its large electrical conductivity. You'd have to build a significantly larger transformer if you wanted to use some other (eg: aluminum) material to deliver the same current through the windings.

    In any case, to add a little to your list :

    Mu-metal : A very high permeability ferromagnetic alloy made primarily from nickel and iron. It is often used in magnetic shielding. ##

    Bismuth : This the the strongest elemental diamagnet at room temperature. It's diamagnetic susceptibility is a little bigger than those of gold and graphite and a lot bigger than those of copper and water, yet about 5 orders of magnitude smaller than that of a superconductor (in the Meissner phase).

    ** It is the weakest known elemental diamagnet, with a susceptibility smaller than -10^-6.

    ## Note : In certain (eg : aerospace) applications where stronger shielding is required, superconductors are used for magnetic shielding. A superconductor is a perfect diamagnet with susceptibility of -1.
    Last edited: Apr 16, 2006
  6. Apr 16, 2006 #5
    thankyou!! these are great examples of the kind of materials i ment
    Last edited: Apr 16, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook