MAGNETISM

WELCOME

-PRESENTED BY,SAGARA SL SURENDRANPHYSICAL SCIENCE.

TYPES OF MAGNET

Types of magnet

Types of magnet

Natural magnet

Artificial magnet

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.

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 .

GENERAL PROPERTIES

GENERAL PROPERTIES

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.

2. Like magnetic poles repel and unlike poles attract.

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.

MAGLEV TRAINS

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 .

MAGLEV TRAINS

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

EARTH AS A MAGNET

The nickel iron core of the earth gives the earth a magnetic field much like a bar magnet

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.

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.

A SMARTPHONE CAN BE USED AS COMPASS

A smartphone can be used as a compass because of the magnetometer inside it.

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.