# Materials that effect fields from Perminant magnets?

1. Apr 10, 2006

### mimic

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

Graphite: A Magnetic Stabilizer
Coper: A Magnetic Inductor

2. Apr 11, 2006

### Astronuc

Staff Emeritus
Materials in what way?

Do you mean materials added to ferromagnetic materials/alloys or surrounding them or juxtaposed?

3. Apr 12, 2006

### mimic

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
4. Apr 16, 2006

### Gokul43201

Staff Emeritus
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.

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.