Sunday, October 26, 2014

HISTORICAL BACKGROUND OF MAGNETISM AND ITS RELATED PROPERTIES

It was known to the ancients that there exists in nature some material which possessed the property of attracting and holding small pieces of iron.

Thales (640 BC - 546 BC) recorded the existence of Asia Minor substance called Lodestone (Magnetite) which had the property of attracting small bits of iron and setting itself in a North-South direction when suspended freely.


The name magnet is derived from that of the ancient town Magnes (now Manissa).

Aristotle attributed the first of what could be called a scientific discussion on magnetism to Thales of Miletus, who lived from about 625 BC to about 545 BC.

Around the same time, in ancient India, the Indian surgeon, Sushruta, was the first to make use of the magnet for surgical purposes.

There is some evidence that the first use of magnetic materials for its properties predates this, J. B. Carlson suggests that the Olmec might have used hematite as a magnet earlier than 1000 BC.

As early as the first century (A.D.)the Chinese had some knowledge of bar magnets and were apparently using a sort of compass to guide them across deserts.

By about twelveth century, a crude form of compass had in fact come into use among European navigators, and this greatly stimulated navigation.

Artificial magnets were formerly made by stroking iron with a natural magnet.

Until about the beginning of nineteenth century, electricity and magnetism were considered unrelated to each other. 

In 1819, Oersted discovered that a magnetic needle is deflected by a current carrying conductor brought near it and thereby discovered the phenomenon of electricity produced magnetism.

It was found that coils carrying currents exhibited properties of resembling those of a magnet.

Then followed the experiments of Biot, Savart and of Ampere which led to the enunciation of the Ampere's rule, Experiments of Faraday and Henry resulted in the discovery of Electromagnetic Induction and its laws.


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