power point presentation on magnetism

1. MAGNETISM
WELCOME

2. -PRESENTED BY,
SAGARA SL SURENDRAN
PHYSICAL SCIENCE.

4. TYPES OF MAGNET

6. NATURAL MAGNET
• Magnets obtained directly from the nature are natural magnets.
• Magnetic properties of the substance are known to people from
ancient times.
• In 800 BC a particular mineral discovered in a place named
Magnesia was found to possess an amazing property that they
could attract pieces of iron .
• It was named magnetite .
• When suspended freely, the pieces of mineral were found to
indicate a particular direction and came to be known as leading
stone.

8. ARTIFICIAL MAGNETS
• Artificial magnets are prepared by men using elements
like iron ,cobalt, nickel or their mixture with other
elements.
• Artificial magnets are much stronger than natural
magnets.
• Depending on the requirements these magnets are
made in various shapes and sizes.

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General properties of magnet
1. Magnets usually have two poles.
• The end of the magnet which points north
when magnet is free to turn on a vertical
axis is the north-seeking pole , simply the N
pole.
• The opposite end which points south is the
south seeking pole.
• Magnets if cut into pieces every piece will
still have two poles.

12. 2. Like magnetic poles repel and unlike poles attract.

13. MAGLEV TRAINS
• Maglev trains or Magnetic Levitation trains are trains
without wheels that move fast over the rails.
• Maglev is a transport method that uses magnetic
levitation to move vehicles without touching the ground.
• With maglev a vehicle travels along a guide way using
magnets to create both lift and propulsion , thereby
reducing friction by a great extent and allowing very
high speed.

14. MAGLEV TRAINS

15. WORKING PRINCIPLE
• The interaction between the magnetic fields created by
electromagnets at the bottom of the train and the magnetic field
resulting from the arrangement of the rails that the train rises a
little above and move forward fast.
• As the movement is one with no contact between train and rails
both energy loss due to friction and noise pollution are reduced .

16. MAGLEVTRAINS

17. WILLIAM GILBERT(1544-1603)
William Gilbert was an English scientist and
physician who is credited by many as the
“Father of Electricity and Magnetism”.
He collaborated with everyone from ships
captains and navigators to compass makers
and performed experiments using a
spherical magnetic lodestone and freely
moving needle.
He observed the magnetic forces produced
circular motion and he connected the
phenomenon of magnetism with the rotation
of the earth.
The earth acts like a large magnet, this was
first discovered by the scientist William
Gilbert.
EARTH AS A MAGNET

18. EARTH AS A MAGNET
The nickel iron core of the earth gives the earth a magnetic field much
like a bar magnet

19. EARTH AS A MAGNET
Earth acts as a large
magnet.
William Gilbert found that
just as the earth has north
and south geographically it
has the north and south
pole when considered as a
magnet.
The south pole of earth’s
magnet is near to
geographic north pole.
The north pole of the earth’s magnet is near to the
geographic south pole.

20. MAGNETIC COMPASS MAGNETIC COMPASS is the
oldest instrument for
navigation and has been a
vital tool for navigators at sea
for centuries.
A magnetic compass work
because earth is like a giant
magnet surrounded by a huge
magnetic field.
The magnetic field of earth
causes a magnetized needle
of iron or steel to swing in
north- south position.

21. A SMARTPHONE CAN BE USED AS COMPASS
A smartphone can
be used as a compass
because of the
magnetometer inside it.

22. N
S
Iron nail
Coil of wire
Electromagnet
When an electric current is passed through a coil of wire wrapped around
A metal core , a very strong magnetic field is produced.
This is called an electromagnet.