Theory:

A magnet were first discovered in Magnesia, a place in Ancient Greece, by a shepherd named Magnus. This ore with the attracting property was named after the shepherd as magnetite.
 
Natural magnets:
 
Magnets are naturally occurring substances with the property of attracting iron. They do not have a definite shape and are also known as lodestones or leading stones since they help in finding directions.
 
Artificial magnets:

The process of converting a piece of iron into a magnet is known as magnetization. By magnetization, different kinds of magnets were produced in different shapes from a piece of iron. These man-made magnets are called artificial magnets.
 
Magnetic materials - Materials that are attracted towards a magnet.
Non-magnetic materials - Materials that are not attracted towards a magnet.
 
Poles:
  • The ends of a magnet that attracts most of the iron filings are called its poles. The magnetic force is maximum at the poles and minimum at the centre of a magnet.
  • North pole - The end of the magnet that points towards the north.
    South pole - The end of the magnet that points towards the south.
  • A magnet, when suspended freely in the air, will always come to rest in the North-South direction.
Direction finder:
  • A compass is a device that is used to find the direction.
  • Chinese travellers used lodestones for navigation in the ocean.
  • Compasses are mainly used in ships and aeroplanes for navigation.
  • Mountaineers carry a compass in unknown places to find their way out.
Action of magnets:
  • A repulsion occurs when like poles (N-N or S-S) of the magnets are kept closer to each other.
    An attraction occurs when unlike poles (N-S or S-N) of the magnets are kept closer to each other.
  • Like poles repel whereas unlike poles attract each other.
Actions that affect the magnetic property:
  • Heating
  • Hammering
  • Dropping the magnet from a certain height
  • Placing the magnets near an electronic device
  • Improper storage
Precautions to retain the magnetic property:
  • The bar magnets are separated by a piece of wood, keeping the unlike poles on the same side with a pair of soft iron pieces across their ends.
  • A piece of soft iron is kept across the poles for a horseshoe magnet like a magnetic keeper.
  • The magnets should be kept away from electronic gadgets as it affects the magnetic property of magnets.
Uses of magnets:
  • Magnets are used to lift heavy metal loads in a junkyard.
  • A crane attached to a magnet separates magnetic materials from the junk.
  • Playing toys and dolls have magnets in them.
  • Magnets are used for navigation purposes.
  • Magnets plays a vital role in small electric motors, magnetic loudspeakers, door locks, bags, pencil boxes, stickers on refrigerators, pin holders, and phone covers.
Levitation - A process in which an object floats in the air without any support.
 
Electromagnetism - When an electric current flows through an iron piece wounded by a coil, it behaves like a magnet.
 
Electromagnet - A type of magnet which produces a magnetic field when an electric current flows through it.
 
Maglev train - An electromagnetic train that works on the repulsion property.
 
Advantages of Maglev train:
  • No friction
  • Can travel at high speed
  • No noise is produced.
  • Consumes less energy
  • Eco-friendly
Countries with Maglev trains:
  • China (Shanghai Maglev train)
  • Japan (SC Maglev)
  • South Korea (KTX)