MIND MAP
DISCOVERY
 A black stone which was discovered in
Magnesia in Asia Minor called Magnetite
could attract iron.
A shepherd discovered Magnets accidentally.
One day, the iron stick that he was carrying
got stuck to a rock and he was unable to pull
the iron away. This led to the discovery of
magnet.
TYPES OF MAGNETS
NATURAL MAGNET


Natural Magnets
A piece of magnetite which is
found in nature and has magnetic
property is called a natural
magnet. Example: lodestone.
Earth as a magnet
Earth behaves like a huge bar
magnet. The north pole of earth’s
magnet is near the geographical
South Pole. The South Pole is near
the geographically north pole. This
is illustrated below
EARTH AS A BIG MAGNET
ARTIFICIAL MAGNETS
A substance to which
properties of a natural
magnet are imparted
by artificial means is
called an artificial
magnet. Example:
Horse-shoe magnet.
Artificial magnets are
found in various shapes
and size.Bar magnet
Horse shoe magnet
Cylindrical magnet
Magnetic needle
Properties of magnets
Attractive
The property of a magnet by virtue of which it can attract all
magnetic substance towards itself.
Magnet attracts all substances made up of iron, nickel, cobalt and
their alloys and these substances are called magnetic substances.
DIRECTIVE
Directive property:is the property observed, when a magnet is freely
suspended, it always points in the north-south direction
As earth behaves like a magnet and its north and south poles are in south
and north direction respectively. So a freely suspended magnet stops in
north-south direction.
BAR MAGNETS
TERMS RELATED WITH IT
Magnetic pole
Magnetic Axis
Magnetic equator
Effective length.
Magnetic pole: The regions near the ends of a bar magnet where the
attractive or repulsive power is most pronounced are called the poles of
the magnet.The pole of a freely suspended magnet pointing towards the
geographic north is called north seeking pole or North Pole.
The pole of a freely suspended magnet pointing towards the geographic
south is called south seeking pole or South Pole.
Properties of magnetic poles:
Magnetic poles always occur in pairs.
Like poles repel and unlike poles attract each other.
Magnetic Axis: The imaginary line (X1 X2) which joins the magnetic
north (N) and south (S) poles of a bar magnet is called magnetic axis.
Magnetic equator:
The imaginary vertical line (Y1Y2), which divides the bar magnet
into two equal parts, is called magnetic equator.
Effective length
Effective length: It is the distance between magnetic north
pole and magnetic South Pole.
Effective length = (7/8) Actual length of the bar magnet
(Approximately)
USES OF MAGNETS /APPLICATIONS
Some of the more common applications of magnets and magnetic
materials are as mentioned below:
a. Magnets are used in magnetic compasses to find the direction.
b. Magnets are used in pencil boxes, refrigerator doors and
electricity meters.
c. Ceramic magnets are used in large computers.
d. Magnets are used in toys to give magical effects.
METHODS OF MAKING MAGNETS
Single Touch Method
This method involves the rubbing of the magnetic substance with a
magnet.
If we will strike an iron bar from one end to other by a magnet about 30 to
40 times by using the same end of the magnet and lift it at the end of each
stroke, the bar will become a small magnet.
CARE THAT SHOULD BE TAKEN
Care And Storing
A permanent magnet tends to lose some of its magnetism with
time. So, it has to be stored in a special way.
The following precautions must be taken for storing magnets:
a. Magnets should never handle roughly.
b. Magnets should never be heated.
c. When we are not using magnets, they should be stored along
with magnetic keepers.
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