Magnetism experts?

[Drizzt]

Is there someone who can help me with magnetism?
I want to try a funny project (a library builts on magnets), but I know anything of magnets...

[Rakido]

You can start here and make your way through the articles

http://en.wikipedia.org/wiki/Magnet



Rakido

[az]

The various articles about rare earth magnets over on www.dansdata.com also contain quite a bit of valuable information.

AZ

[DukeP]

Dansdata is a real nice space, thats for sure!
Although his site is very cluttered, his articles are almost always exellent.

~DukeP~

[Drizzt]

Thx all, I'll take a look. Hope I will obtain what I want, it would be very nice

[Brian R.]

I didn't read every article to see if it's mentioned, but I didn't see a reference to or mention of circular magnetism.

There are two types of magnetism you can induce into an object. Longitudinal magnetism and circular magnetism. Longitudinal magnetism is the common variety where you have the lines of force traveling down the bar lengthwise and coming out the ends of a bar. They are actually both internal and external to the bar. The portion of the flux lines external to a bar results in an attractive force to other ferromagnetic materials. Circular magnetism has the lines of force totally within a cylindrical bar and they travel around the axis instead of along the axis. They never exit the bar. Flaws in the metal structure or edges on the bar (like square bar stock) permit points where the flux lines exit the bar, but in general, the lines of flux are not external to the bar.

Longitudinal magenetism is induced by a circular electric current (longitudinal magnetic field) and circular magentism is induced by a longitudinal electric current (circular magnetic field). You induce longitudinal magnetism in a ferromagnetic bar by placing it in a coil and passing DC current through the coil. You induce circular magnetism in a bar by passing DC current through the bar lengthwise. The induced magnetic field is always orthogonal to the direction of the applied current.

You demagnetize an object by subjecting it to a coil of AC current and withdrawing the object from the coil while the current is flowing.