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Diamagnetic Water
As we discussed on our diamagnetism main page, water is diamagnetic,
though about 20 times less than Carbon-Graphite or Bismuth. When exposed to a magnetic field, it
produces a weak magnetic field in the opposite direction. Also, this means it is repelled by a
magnetic field. This page shows some simple experiments that
demonstrate the diamagnetic properties of water.
One of our
goals up here at Wondermagnet Laboratories is to get a tiny drop of water to levitate above four permanent
magnets, like in our levitating carbon-graphite chip experiment. It's
probably not possible with currently available grades of magnet, but as N-I-B magnets improve in
quality, it may be possible soon. Scientists at the University of Nijmegen (Holland) high-power
magnet labs successfully levitated a small frog
over a very powerful superconducting electromagnet...it
worked because of the diamagnetic properties of water, protein and DNA in the frog's body.
Experiment 1 -- Oil Drops and Water
Fill a small glass jar 2/3 full with rubbing alcohol. Add a couple drops of vegetable oil, which
will fall to the bottom of the jar.
Add water a little bit at a time, gently swirling the jar, until the specific gravity has been
adjusted so that the oil drops neither float nor sink--they will be suspended in the middle.
BEFORE MAGNET
Add a bunch more tiny oil droplets, set on a countertop, and place a large N-I-B magnet or
stack of magnets next to the jar. The stronger the magnet, the faster the droplets move. We used our
Item #37, one of the largest, most
powerful N-I-B magnets available--but stacks of smaller magnets will work in this experiment also.
You should be able to see the oil droplets slowly migrating toward
the strong magnet. After a few minutes, they will collect around the pole of the magnet:
AFTER MAGNET
The magnet is repelling the water in the mixture, causing the oil droplets to collect at the
area of strongest magnetic field.
Experiment 2 -- Magnet Bends Water Surface
This experiment gives a very subtle result that can be hard to see. When it can be made visible, it's
quite dramatic. We've tried to come up with ideas
for better visibility that allow this experiment to be performed as a classroom demonstration. Please let us know if you have any ideas about this!
Place the strongest N-I-B magnet you can find at the bottom of a shallow tray or petri dish. Fill with
water so the magnet is just barely covered. You'll have to cover it enough so that it's obvious that
the force at work is NOT surface tension--1/8 to 1/16 of an inch covering the magnet is ample. If there
are real skeptics
in your audience, put only an 1/8 to 1/4 inch of water in the petri dish, and place the strong magnet
UNDERNEATH the dish--the effect still works, proving that surface tension is not causing it. Perform
this experiment on a sturdy surface like a workbench or countertop, as vibrations will cause enough
ripples that the effect won't be visible. We used our
Item #11 for these photos.
The visible effect is a depression in the water's surface over the pole of the magnet. The magnet
is repelling the diamagnetic water, pushing it off to the sides. It's a subtle effect, so try these
tips for demonstrating it:
- View the water's surface at an angle, and watch for distortions in the reflection from the
water's surface. Viewing the reflection of a piece of window screen, mesh, or even a chess board
seems to work best...you can see the surface distortion best against a reflected grid pattern.
Distortion of grid pattern from magnetic repulsion of water
- Or, shine a bright light on the water's surface and view the reflected beam as projected on a wall.
Try it without the magnet to see the difference. You can use a black matte-surfaced magnet if
reflections from magnet plating cause problems...in our photo below they did not. The uppermost splotch
of light in this photo is from water surface distortion caused by the magnet.
Distortion of light beam reflection from magnet.
Diamagnetic Icicle
Hang an icicle from a piece of thin fishing line. Tie it so the icicle is balanced--you can also cast a piece
of ice in the freezer that is a long cylinder to make it easier to balance. Bring a strong N-I-B magnet or
stack of magnets toward one end of the icicle, and it will spin slowly away from the magnets. We tried it
with an ice cube without success--the longer lever arm of the icicle makes it possible. Also, we
tried it with thread instead of fishing line, and the twist in the thread trying to unravel made the
icicle spin hard enough that the diamagnetic repulsion could not overcome it.
We will gladly accept, review and consider your science experiment submissions for inclusion on this site, whether you are age 6 or age 100! Email us for details.
Every experiment on these pages must be done with adult supervision only!!! If you are already an adult, we recommend getting a friend to help so you don't do anything childish and hurt yourself. We'll try to provide safety warnings, but cannot be held responsible for your own safety. Many of these experiments and many of the books we sell are from another era when safety was not a consideration, so PAY ATTENTION to the hazards of what you are doing! Wear safety goggles and gloves. Don't be stupid--YOU are supposed to be the adult here!
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