All About Magnetism and Electromagnetism How It Works
All About Magnetism and Electromagnetism How it works Tutorials
Magnet
A magnet is a substance that attracts pieces of iron. The phenomenon by which this attraction takes place is called magnetism.
Magnets are two types
Natural Magnets
The natural magnets are those iron ores which are obtained from mine and have the property of attracting iron pieces naturally.
Artificial magnets
The artificial magnets are those which are created by artificial means. An artificial magnet can be further divided into two types are temporary magnets and permanent magnets.
Temporary magnets
A temporary magnet is that in which magnetism remains temporarily. If a wire is wound on a soft iron piece and direct current is passed through the wire, then soft iron piece becomes a temporary magnet. It is because the iron piece will retain magnetism so long as the current is flowing.
A Permanent magnets are made from steel which is in general harder than soft iron apart from steel, alloys like cobalt steel, tungsten steel, etc. are also used as permanent magnets. These are used in Direct current machines to create magnetic flux, electrical instruments, moving coil loudspeaker etc.
Properties of Magnet
1. A magnet always attracts iron and its alloys
2. The magnet has two poles and when it is freely suspended it comes to rest pointing north and south directions. The end which points towards north is known as North-pole and the other which points toward south is known as South-Pole. The attracting power of the magnet is concentrated around two points one each at end ends.
3. Like poles repel and unlike poles attact each other.
4. If a magnet is broken into pieces, each pieces becomes and independent magnet.
5. A magnet can import its properties to any magnetic material.
Magnetic effect of electric current
When and electric current flows through a conductor, a magnetic field is set up all along the length of the conductor. In this connection following are the important points worth noting.
1. The magnetic lines of force are circular in a plane perpendicular to the current.
2. The field near the conductor is stronger and becomes weaker as we go away from the conductor.
3. The magnetic field becomes stronger if current is increased and vice-versa.
4. The direction of the field is reversed it current is reversed.
Facts of Magnetism and Electromagnetism
1. A magnet is a piece of iron or other magnetic material which can attract small pieces of thesematerial towards it.
2. A freely suspended magnet always rests in north south direction.
3. A natural magnet is called lodestone.
4. A magnet is able to attract nickel, cobalt and steel.
5. Externally, magnetic line of force travels north to south.
6. A material commonly used for shielding or screening magnetism is soft iron.
7. Magnetism is the property of certain materials of attracting small iron pieces toward them.
8. The magnetism that remains in a magnet after the magentising force has been removed is called its residual.
9. Iron becomes magnetized by induction when it is near to one end of a magnet.
10. Magnetic lines of force are called flux.
