MAGNETISM
We cannot see or feel the force of magnetism. But it is all around us since the Earth is itself a giant magnet. A magnetic force affects mainly objects and substances that contain the metal iron. It pulls or attracts them. The force is present as a magnetic field around a magnet, which is itself usually made of iron.
Magnets of different sizes and shapes have hundreds of uses, from holding notes on a refrigerator to being vital parts in electrical generators, motors and loudspeakers.
A magnet does not always attract another magnet. Its magnetic force is strongest at two areas called its poles. These are different from each other and known as north and south poles. The north pole of one magnet attracts the south pole of another magnet. But it pushes away or repels the other magnet’s North Pole. The general rule is that unlike poles attract, like poles repel.
A bar magnet is a strip of iron or steel in which the atoms are lined up in a certain way. Its magnetic force is strongest at its two ends or poles.
The Earth has a magnetic field and two magnetic poles, north and south, almost as if it had a giant bar magnet inside.
A magnetic compass is a needle-shaped magnet. Its poles are attracted to the Earth’s poles so it always turns to point north-south.
ELECTROMAGNETISM
Electricity and magnetism are two aspects of the same force, called the electromagnetic force. They are so closely linked that one can produce the other. A magnetic field moving near a wire causes electricity to flow in the wire. An electric current flowing in a wire makes a magnetic field around the wire. Twist the wire into a coil and it produces a stronger magnetic field. It can be turned on and off by switching the electricity on and off. This is an electromagnet. Electromagnetism is the basis of electric motors and generators.
A maglev (magnetic levitation) train uses the pushing force between the like poles of magnets in the train and track. The force holds the wheel-less train above the track.
Picture Credit : Google