MIND MAP

FUN WITH

MAGNETS

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 MAGNETEARTH AS A BIG 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 magnetEarth 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

ARTIFICIAL MAGNETSA 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

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. 

Properties of magnets

 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.

DIRECTIVE

BAR MAGNETS

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.

TERMS RELATED WITH IT

     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.

Properties of magnetic poles:

The imaginary vertical line (Y1Y2), which divides the bar magnet into two equal parts, is called magnetic equator.

Magnetic equator: 

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)

Effective length

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.

USES OF MAGNETS /APPLICATIONS

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.

METHODS OF MAKING MAGNETS

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. 

CARE THAT SHOULD BE TAKEN

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