I won`t send any more until I have assessed the `mood` of the list - but I
haven`t seen this anywhere else and it does add fuel to our thoughts about
magnetic motors etc.
Thanks for your patience
Nick Hall
---------------------- Daily Telegraph Friday 28th March 1997 --------------
Gravity is leap-frogged by a magnet
By Aisling Irwin, Science Correspondent=20
A DUTCH frog may have become the first living creature to
experience levitation. Physicists made it rise and hover in the air using a
strong magnetic field. They repeated the procedure with a cheese sandwich.
The physicists say the technique could be used on human
beings, but they would need a magnet with a very strong - and therefore
expensive - magnetic field gradient. Living things have been raised before
by putting them on magnetic platforms which are exposed to magnetic fields.
But the frog was lifted, without a platform, by the action of the magnetic
field on each molecule in its body.
The physicists, led by Dr Andr=E9 Geim, of Nijmegen
University in the Netherlands, used a large super-conducting magnet. Such
magnets are usually cooled to temperatures that a living thing could not
survive. But this one had a "bore" down the middle which remained at room
temperature.
The scientists exploited a weak type of magnetism
possessed by every material - molecular diamagnetism. This differs from
other types of magnetism: ferro-magnetism, which is possessed by horseshoe
magnets, and paramagnetism, which is possessed by materials attracted to
ordinary magnets.=20
Molecular diamagnetism is millions of times weaker than
ferro-magnetism, and repulsive. So if any material is put into a strong
enough magnetic field it will move away from the force. The field distorted
the motion of electrons in each of the frog's molecules. Once the magnetic
force balanced the force of gravity, the frog levitated. According to
Physics World, which reports the levitation in its April issue: "The frog
looked comfortable inside the magnet."
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"That which a man cannot afford to loose owns him"
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