Diamagnetic Levitation Using Silver

by David Fiedler

(click any image for a bigger version)

When I first heard of diamagnetic levitation, I was fascinated and I knew I just had to do it. The way it works is simple: diamagnetic materials are slightly (very slightly) repelled by magnetic fields, so if you have a relatively massive piece of diamagnetic material, a small, powerful magnet will itself be pushed away by this effect. Putting the magnet between two pieces of diamagnetic material would cause it to float between them if the magnet is light and powerful enough, the pieces close enough, and there is no gravity.


If you happen to be in a gravitational field, all you have to do is put a more powerful magnet (or a stack of them) above the "diamagnetic sandwich" to compensate for gravity, and you have levitation.

The addition of the plastic "surround" was my idea to support the magnet assembly from the top, and also protect the "floating" magnet from air currents (since it's not touching anything and is levitating, it tends to be rather sensitive to anything in the air, including moth turbulence).

Here's a closeup of the gravity compensating magnets. All of them are NIB type (neodymium-iron-boron) and include ring magnets, a disc magnet, and a reclaimed magnet from a hard disk drive. I recommend the wonderful folks at Wondermagnet if you want to buy some of your own.



All the hoi-polloi use carbon graphite or bismuth for diamagnetic plates, so I decided to use slabs of pure silver instead :-). Seriously, I did get a couple of pounds of bismuth (cheapest source: United Nuclear), but I followed the usual instructions on the Web about using the bottoms of soda cans as molds and they ended up too rounded. I found that it's important to have the diamagnetic slabs as smooth and flat as possible, otherwise the "floating" magnet is not stable. So I will be remelting the bismuth into flat-bottomed muffin tins, but for now remembered that I had some 10 ounce ingots of silver laying around and used those after reading that silver was diamagnetic too. And it worked!


My friend Dave Hampton was the one who gave me the idea to work with silver in the first place; I showed him the gravity tricks with copper and magnets, and he instantly suggested that silver would work well too, since it was near copper on the Periodic Table and it's even a better electrical conductor. Pretty quick for an 18-year-old!

Here I show proof that even AOL discs are good for something.



Closeup of levitating magnet
A final closeup. If you don't believe it's really floating, click on the picture!

Oh, just a question for you scientist types: if I am lifting and holding up a mass in a gravitational field at room temperature with no moving parts and I am not breaking any laws of physics...where is the power coming from?

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