DISCOVERY OF MAGNETS
Legend has it that a shepherd named Magnes used to take a stick with him whenever he took his herd of sheep and goats to the nearby mountains for grazing. The stick had a small piece of iron on one end. One day he put his stick on a rock. When it was time to go, he tried to pick up the stick but noticed that it was difficult to pull away he iron from the rock. It was as if the rock was being attracted towards the rock. That is how natural magnets were discovered.
This property due to which a substance attracts iron is called magnetism. Such substances are called magnets.
Natural magnets come from magnetite. Magnetite contains iron and exhibits magnetic properties. Nowadays magnets can be made from pieces of iron. These are called artificial magnets and are made in different shapes like horse shoe magnet, bar magnet, etc.
The materials which get attracted by a magnet are called magnetic materials. E.g.: Iron
The materials which do not get attracted by a magnet are called non-magnetic materials. E.g.: Wood
POLES OF MAGNETS
- The ends of a magnet are called its poles. A magnet has two poles regardless of its shape. These are the North and South poles which are marked on the magnet as ‘N’ and ‘S’ respectively.
- A freely suspended bar magnet always points in the North-South direction.
- The North pole of the magnet always points towards the North pole of the Earth and the South pole of the magnet always points towards the South pole the Earth.
- A compass is a small box which has a magnetised needle pivoted inside it. The box also has a glass cover on it. The needle inside is free to rotate over a dial which has directions marked on it.
- A compass is mainly used for navigation purposes.
LIKE POLES AND UNLIKE POLES
It is observed that like poles repel each other. However, unlike poles attract each other.
Note that magnets may lose their properties if they are dropped, heated or hammered. The magnets become weak if they are not stored properly. Therefore, magnets should be stored properly and carefully.