In the ancient times, it was a
known fact that pieces of iron metal from the Magnesia region in Little Asia had magnetic qualities. It is after
this region that the name 'Magnet' was awarded to
everything that portrayed this phenomenon of
Magnets come in different shapes and
sizes. For example: rod magnets, needle magnets,
horseshoe-shaped magnets, semi-circular magnets, etc.
A magnet consists of two poles, a North
pole and a South pole. These
two poles are inseparable; one cannot exist without the other. If one divides a magnet into units then each unit will contain its own north and south poles. It is these units that assert
their influence the most i.e. the poles have the strongest magnetic force.
Magnetic field is the space around a
magnet in which a different magnet is affected by the
force field, from the first. The strength of a magnetic
field depends on the amount of force-lines per unit area.
This unit strength is measured in Gauss, Oersteds or
Tesla, terms made after the names of the physicist who
worked out these measures.
The earth is also considered as a gigantic magnet
wherein its magnetic field-strength lies at around
0.3-0.47 Gauss on the surface. The earth is surrounded by an
atmosphere which consists of different electrical fields.
As the earth possesses magnetic materials, these currents
produce a magnetic earth field. Earth's magnetism changes according to daily and yearly fluctuations. These fluctuations are brought
about mainly due to changes in the
sun's magnetic field. The sun's rays affect the top layers of the atmosphere causing changes in the earth’s magnetic field, which in turn affects many biological processes in
Apart from the earth and the sun,
other planets like the moon, stars, etc. also have magnetic fields.