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Living with magnetism

Anyone who lives on earth – or indeed any rotating planet with an iron core – is living with magnetism. There is no escaping it. In fact we would find it very hard to live without it as it is responsible for an electromagnetic barrier that protects us from harmful radiation.

Our awareness of magnetic fields is generally through practical experience of its effects rather than direct knowledge. In some ways this is different to gravity, a force with which magnetism is sometimes compared. But we are aware of gravity directly, every time we drop something, every time we carry a heavy shopping bag and every time we climb the stairs. Magnetism on the other hand, doesn’t reach our senses in the same way, certainly not consciously.

Of course we can see magnets in action when we actually hold one and use it to pick up a pin or a nail or an iron screw. However if we looked more closely, we would see an abundance of indirect evidence of magnetism all around us.

The name magnetism is actually derived from a place – Magnesia – somewhere in Macedonia where naturally formed magnets were available in abundance. It was described by Plato circa 400 B.C. the ancient Chinese also knew not only about magnetism but even about earth’s magnetism and there is evidence that they created a magnetic compass for navigational purposes in the third century B.C.

Rather symbolically, they fashioned it like a spoon that rested on a flat surface, rather than a hinge or suspended from a string. The reason this was so symbolic was because it was known that the last two stars of the constellation ursa major point to the pole star (which is seen directly north in the northern hemisphere) and ursa major looks like a spoon.

Many years later, Arab merchants who travelled to and from China on the famous Silk Road, brought back more developed versions of the same invention along with the magnetic material that it was made from. They called this material lodestone (sometimes spelt loadstone). This name meant “leading stone.” and it was the first magnetic material used by Europeans. The modern name for this material is magnetite.