Magnetism and Electromagnetism

What is a Magnet ? What are its Properties ?

Magnet is the substance  having the properties of attracting and its alloys.

the magnets have certain properties which are:

1. the magnet always  attracts iron and alloys.
2. the magnet has two poles and when it is freely suspended, it comes to rest pointing north and south direction. the end, which points towards north is known as north pole and the other, which point towards south is known as south pole.
3. like poles repel and unlike poles attract each other.
4. if a magnet is broken into pieces, each pieces  becomes an independent magnet.
5. A magnet can impart its properties to any magnet material.

What are the two general classes of magnet ?

Magnet may be divided into two general classes:

1. Natural Magnet
2. Artificial Magnet

1. Natural magnet: the magnet found in nature is known as lodestone or leading stone as it was used by navigators in sea, etc. the natural magnet has chemical composition of Fe₃O₄.
2. Artificial Magnet: the magnet prepared by artificial methods is called artificial magnet. it is classified as:

1. Permanent  Magnet 
2. Temporary Magnet or Electromagnet

1. Permanent Magnet: the magnet which retains the magnetic for properties for a long-period is known as permanent magnet. the permanent magnet are available in different shapes as (a) bar magnets, (b) U- shaped, (c) Horse shoe magnet, and (d) Compass needle, etc.
2. Temporary Magnet Or Electromagnet: the magnet which loses its properties as soon as the magnetising force is removed, is generally known as electromagnet.

Classification Of Magnet

(1)Natural Magnet                                                                                           (2)Artificial Magnet

Temporary Mt. Electromagnets

(1) Lodestones or Leading stones    (2) Permanent magnets

1.Bar Mt. 2.U-Shaped Mt. 3.Horse shoe mt. 4. Compass Mt.

To Magnetise a Given Bar: place the iron bar or needle AB on the table and hold a bar magnet as with its north poles near the end N. Rub the magnet from one end to the other along the length of the needle, every time lifting the magnets and  placing it at the end N. Repeat the process by turning over the needle. the end S of the needle  where the rubbing magnet leaves it will show a polarity opposite to that of the rubbing pole. to test the polarity of the magnetised  knitting needle, or bar bring  its either end in turn towards the north pole of the compass needle. it will be noted that there is a repulsion with the end N and attraction with the end towards the south pole of the compass needle. it will be notice the there is an attraction with the end N and repulsion with the end S. showing thereby that the end B is a south pole and end N a north pole.