Introduction

Magnet

Any substance which possesses the following two properties is called a magnet.

(i)It attracts small pieces of iron towards itself.

(ii)It always comes to rest in the north-south direction when suspended freely on Earth.

Lodestone and magnetite’s are natural magnets because they are found in nature.

Artificial magnets are prepared by man to be used at any time and at any place. These magnets are much stronger than lodestone.

Properties of Magnet

1. Attractive: A magnet attracts small pieces of iron, nickel, cobalt, etc. The magnetic force of attraction is maximum is small regions near the ends of the magnet. These are called the poles of the magnet.
2. Directive: A freely suspended magnet always points in north- south direction. The end pointing towards north is called north seeking pole or North Pole. The other end which points towards south is called south seeking pole or South Pole.
3. Law of magnetic polar: There are two poles in a magnet north and south polar. Like poles repel i.e. south repels south and North repels North
4. Unlike poles attract that i.e. north and South attracts.
5. Magnetic polar always exist in pair: It means that even the smallest possible magnet will have both North and South Pole.

Let us take on arbitrary magnet and break into plates.         

Therefore, even after breaking the magnetic into multiple pieces the North and South pair of poles are not lost until it is a magnet.

Some commonly used artificial magnets:

1.Bar Magnet: It is a magnet in the form of rectangular bar, and has two magnetic poles north (N) and South(S) of equal strength.

2.Magnetic needle: It is a magnet tapered towards both ends and pivoted at the centre. It is used to check the direction of a magnetic field and to map the lines of force of other magnets.

3.Horse shoe magnet:It resembles a horse shoe, hence the name.

4.Magnetic compass:

It consists of a magnetic needle pivoted at its centre and encased in a brass box with a glass top. It is used to find direction.

Artificial magnets are preferred to natural magnets. The strength of an artificial magnet is much more than a natural magnet and it can be increased to desired level. Natural magnets come in irregular shapes whereas artificial magnets can be casted into any desired shape or size.

Illustration 1: Why does a compass needle get deflected when brought near a bar magnet?

Solution: A compass needle gets deflected due to forces acting on its poles due to the magnetic field of the bar magnet.