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Letter: Letters: Monomania

Published 29 May 1993

From PAT DELGADO

It has come to my notice recently that monopoles, magnets which have a like
pole at either end and the opposite pole in the middle, are stimulating
extreme interest, especially in Japan. Indeed, I recently received two
samples that had been painstakingly made in Japanese laboratories by placing
steel bars in contra-wound coils in series carrying a DC current.

To me, it seemed that by clamping two ordinary bar magnets together where
their same poles meet, you could achieve the same effect with far less fuss,
so I tried it and it worked. Observations with a compass showed that at a
given distance from the magnet surface, the force at the centre was twice
that at the ends.

Seeing that this worked, I wonder what would happen if the idea was extended
to four magnets linked together at the hub by their same poles, then eight
magnets, and so on until you had a disc with a rim and core of opposite
polarities? And what about extending that to a sphere? What happens to the
core polarity and the magnetic field? What would happen if this sphere were
placed inside another whose inside surface was of opposite polarity, for
example? These intriguing possibilities sprang to mind, and I wonder whether
any of your readers have any answers to these riddles.

Pat Delgado
Alresford, Hampshire

Issue no. 1875 published 29 May 1993

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