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Name:  Sam J.
Status:  student
Age:  20s
Location: N/A
Country: N/A
Date: 2000-2001
Question:
I am tring to find out a good diamagnetic material for magnetic levatation. I know that Bismuth is the best diamagnetic material. But with respect to Carbon-Graphite. I have seen experaments using this and it works well. I was wondering if you could use just carbon or just graphite, and what would work better. Is it a combination of carbon and graphite that works best or is one just a filler? Would using just carbon work better, or just graphite I also heard that the more dense the carbon is, the better it works. I just tring to find the best combination to use that will levatate the best. I plan on getting the matrial in tile form so I can cover a desk and levatate a magnet over it.

Replies:
Sam,

Actually, graphite IS carbon. Carbon-Graphite is carbon in graphite form. Carbon atoms tend to join together in one of three patterns, depending on how hard they are pressed together. Under very high pressure, carbon will form a crystal pattern people like to call diamond. Under more mediocre conditions, carbon tends to form coal. If presed together very lightly, often when deposited near the surface, carbon tends to form a pattern called graphite.

Graphite is a pattern of sheets laid on top of sheets. The carbon atoms form a sheet of hexagons, each carbon joined to three other carbons. Since carbon can bond with four atoms, the fourth connection extends up or down from the sheet for each atom. This joins to an atom in an adjacent sheet. Graphite has very weak bonds and a great deal of open space. This is what makes it such a wonderful substance to put inside a pencil. When you write with a pencil, you deposit carbon atoms on the paper.

Dr. Ken Mellendorf

The only way you will be able to actually get the magnet to levitate indefinitely is to use a superconductor as the diamagnet. Otherwise the eddy currents induced in the diamagnet will fade due to electrocal resistance, allowing the magnet to approach ever closer.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois


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