11 January 2014

Magnetic and Non-magnetic Materials

A Greek shepherd named Magnes discovered magnets 4,000 years ago in Magnesia, Greece. The name magnetite has been derived from Magnesia or Magnes. Magnets are named after Magnetite.
Magnets attract magnetic materials. Natural rocks that have the property of attracting iron are called naturals magnets.  

Magnes discovered a natural magnetic rock, called the lodestone. In the form of a bar, it was used to find directions on the earth, and so the name, ‘lodestone,’ which means the stone that leads.  Lodestone has a compound of iron called magnetite. These natural magnets have the magnetic property of attracting materials like iron. 

 "Archimedes", the ancient Greek scientist, is believed to have used lodestone to pull nails from enemy ships. Taking the nails out made the ships sink.

Magnetic Materials

Materials that are attracted by a magnet are called magnetic materials. Objects made of materials such as iron, cobalt and nickel are magnetic objects. Examples of magnetic materials include iron nail, key, metal spade, needle and metal door handle.

Non-Magnetic Materials

Materials that are not attracted by magnets are called non-magnetic materials. Modern coins are made of uniform mixtures of different metals so they become non- magnetic. Examples of non-magnetic materials include rubber, coins, feather and leather.

Properties of a Magnet

Substances that possess the property of attracting iron are called magnets. The two ends of a magnet are called its poles. All magnets have two poles, and they are called dipoles. A magnet with a single pole doesn't exist. Since poles have high magnetic power, they attract objects easily. The poles of a magnet are named as the north pole and the south pole. In order to identify the poles, the north pole is usually painted in red colour. The other end of the magnet will, therefore, be the south pole. In laboratories, magnets are painted completely red in colour with a white dot to indicate the north pole. The other end will, therefore, be the south pole. A magnet can be cut into two pieces. Each piece will behave like an independent magnet, with a north pole and a south pole.

Types of magnets

Bar magnets

In these magnets, the poles are located at the ends of the bar.

Cylindrical magnets

In these magnets, the poles are located at the two circular ends of the cylinder.

Dumb-bell shaped magnets

In such magnets, the poles are located at the two dumb-bell shaped ends.

Horseshoe magnets

In these magnets, the poles are located at the two free ends of the 'U' shape.


compass is an instrument that is used to find the directions. It has a thin magnetic needle supported from a pivot so that it can rotate freely. The needle is placed over a dial with the directions marked. The entire assembly is placed inside an airtight box.
The north pole of the magnetic needle is painted red. The magnetic needle in the compass points in the north-south direction. By aligning the dial properly, the directions can be found. In the ancient days, an old pointing device, called the south pointing fish, was used to know the directions.  The head of the fish pointed towards the south.

Alignment of a compass

Take a compass and make sure that the magnetic needle comes to rest. Rotate the box so that the red tip of the magnetic needle coincides with the north mark of the dial. The compass is now aligned. Next, select any object around you. Then, with the help of the compass, identify the direction in which the object lies relative to you.

Law of magnets

Unlike poles attract each other and like poles repel each other.

Artificial magnets

Magnets can be made artificially, too. A rectangular iron bar, an iron needle, a blade or an iron nail can be turned into a magnet by rubbing a bar magnet over it.

Precautions to protect magnets from losing their magnetic properties

  • Never drop magnets from heights.
  • Never heat a magnet.
  • Do not hammer a magnet.
Certain items such as CD's, DVD's, debit cards, credit cards or ATM cards, audio and video cassettes, and mobile phones contain magnetic material.   Keep them away from magnets to prevent damage.

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