Magnetism , Magnet properties , types and uses
Magnetism is the ability of the magnet to attract magnetic materials , 2000 years ago , the ancient Greeks found a type of black rocks located in an area named Magnesia , This type of rocks has an attraction force to any material made of iron , So , scientists called this black rock ” natural magnet ” and its attraction force ” magnetism ” .
Types of magnet
Magnets are classified into two types which are natural magnet and artificial magnet , Natural magnet is a black rock , It is one of the iron ores which is known as Magnetite .
Artificial magnet is a magnet made by man , It has different shapes and sizes , Shapes of artificial magnet are horse-shoe magnet , ring magnet , needle magnet and bar magnet .
But , the magnet attracts some materials and does not attract the others , So , the materials are divided into two types according to the ability to be attracted , which are magnetic materials and non-magnetic materials .
Magnetic materials are the materials which are attracted to the magnet , such as iron , nickel , steel and cobalt , Non-magnetic materials are the materials which are not attracted to the magnet , such as chalk , glass , paper , aluminium , copper , wood , leather and plastic .
The magnet attracts metallic paper clips , but does not attract copper wire , because paper clips are magnetic materials , but copper wire is a non-magnetic material , The magnet is used in making the doors of refregirators and the small toys sticking on them .
Properties of magnet
- The magnet has two poles .
- Freely suspended ( moving) magnet always takes a fixed direction , which is north-south direction .
- The like ( similar ) magnetic poles repel each other , but the dislike ( opposite ) magnetic poles attract each other .
- Magnet is surrounded by an area called the magnetic field .
The regions of the magnet which have the most attraction force are the two ends which are called two poles of magnet , To differentiate between the two poles of magnet , the north pole is often red-coloured , but the south pole is often blue-coloured .
Two poles of magnet ( magnetic poles ) are the areas ( regions ) of the magnet which have the most powerful force of attraction or the areas of the magnet where most of the attraction force ( magnetism ) is concentrated .
When you approach a magnet to some iron nails , the most of them are attracted to the two poles of the magnet , because the attraction force of the magnet is concentrated at the two poles of the magnet .
One pole of the magnet tries to search for the north direction of the Earth , while the other pole tries to search for the south direction of the Earth , Freely suspended ( moving ) magnet always takes a fixed direction , which is north-south direction .
The pole of magnet which points to the north direction is called north pole ( N ) , but the pole of magnet which points to the south direction is called south pole ( S ) .
The similar ( like ) magnetic poles repel each other , but the opposite ( dislike ) magnetic poles attract each other , The north pole of a magnet attracts the south pole of another magnet , but repels the north pole , because the opposite magnetic poles attract each other , while the similar magnetic poles repel each other .
The magnetic field is the space around the magnet in which the effect of the magnetic force appears , The magnetic force is the ability of the magnet to attract the magnetic materials existed in its field .
The magnetic force is an invisible force , so , we use the iron filings to see the magnetic field that is formed by the effect of magnetic force .
The magnetic field around the magnet takes a regular shape , the greatest magnetic force of the magnet is concentrated at the two poles of magnet .
Uses of magnet
Making the magnetic compass is one of the uses of magnet in our daily life , The compass is a needle magnet that takes a fixed direction which is north-south direction .
Long time ago , the Chinese used the magnetic rock that spins freely taking a fixed direction which is north-south direction , A Chinese major general depends on this idea in leading his army through dense foggy areas .
In 1600 , the English scientist William Gelbert took the idea of magnetic rock and made a small magnetized needle that is light for spinning freely , This magnetized needle was the basic idea in making the compass .
Compass structure : It consists of a light and small magnet ( magnetic needle ) that can spin freely around a fixed axis , where the north pole of this magnetic needle refers to the north direction of the Earth and its south pole refers to the south direction of the Earth .
The compass is used to locate ( identify ) the main four geographical directions , because its magnetic needle always points to the north and south directions .