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INTRODUCTION
Magnetism is the force, present in and between all objects, that is produced by the motion of electrons – and that results in the attraction and repulsion of different objects.
It is a ‘noncontact’ force that affects every single different object in the world, to a greater or less extent, and that is the result of the movement of these subatomic particles, electrons, and their electric charge
Magnets are substances that are able to attract and hold items.
Lodestone is the only known natural magnet which was discovered by the Chinese 2,000 years ago.
Other magnets produced artificially by man are called artificial magnets.
Magnets and Non-Magnetic Materials
Magnetic materials are those that are strongly attracted by magnets while non-magnetic ones are those that are not affected by magnets.
Iron, steel, cobalt and nickel are magnetic substances, while wood, glass and copper are examples of non-magnetic substances.
Substances that are repelled by magnets are said to be diamagnetic whereas those which are strongly attracted i.e. iron, nickel, cobalt are called ferromagnetic materials .
The materials that are so lightly attracted such that the magnet seems to have no effect on them are called paramagnetic materials (mostly non-magnetic materials).
Ferrites are a mixture of iron oxide and barium oxide are the most newly developed magnetic materials.
Ceramic magnets or magnadur magnets are made from ferrites and are very strong.
Properties Of Magnets
- They are double poled substances with both the North and South poles.
- Like poles repel and unlike poles attract. Repulsion is a sure method of determining whether two substances are magnets.
- The greatest magnetic force is concentrated around the poles of a magnet.