How to Test diamagnetism: Antimagnetic water/hanging graphite

If you had to answer the following statement, which answer would you choose?

Water is:
A) Attracted by a magnet
B) Repelled by a magnet
C) Completely non-magnetic

Most would choose "C" - but really, water is slightly repelled by magnets.

Watch this science video tutorial from Nurd Rage on how to test diamagnetism with antimagnetic water and levitating graphite with Dr. Lithium.

Diamagnetism is the property of a substance to be repelled by a magnetic field. Interestingly enough, water shows this effect. We build a simple, but very sensitive detector to show this. We also show pyrolytic carbon that is so diamagnetic that it can float above magnets if they are arranged the right way.

Water is diamagnetic, meaning it's slightly repelled by a magnetic field. But in everyday life this is almost impossible to notice. We need to build a very sensitive detector to see it.

Just get a basin of water and float a styrofoam block in it. Styrofoam is very light and so even the small repulsive force of a test tube of water will have a noticeable push on it. Push the test tube of water into the center of the block and simply hold a strong neodymium magnet as close as possible to the tube without touching it. It's a very small force, but eventually the block will start moving away from the magnet.

Pyrolytic graphite, also called pyrolytic carbon, exhibits the same effect and can even be made to levitate on top of a magnet. A single magnet is unstable since the graphite will like to fall off the side. But having four magnets and arranging them like in the video will create a "void" in the center that the graphite "falls" into and remains stably levitated.

Some online dealers selling pyrolytic graphite: K&J Magnetics, Science Toys, & DigiKey.

Brought to you by one of WonderHowTo's favorite scientists, NurdRage.

1 Comment

can this be used to say..create a small desktop sculpture/knickknack? or would disguising/decorating the magnets and diamagnetic material stop the repeling effect ?

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