Magnetism is the force of attraction or repulsion exhibited by a magnet.

A magnet is a material that can attract objects made of iron, cobalt, or nickel.

The invisible force that acts around a magnet is called the magnetic field.

(a) Natural Magnets (Lodestone)

1. Found naturally in the earth


2. Lodestone is a naturally magnetized mineral that attracts iron


3. Example: Lodestone used in early compasses for navigation

(b) Artificial Magnets

1. Made by humans using iron, steel, or other magnetic materials


2. Examples: bar magnet, horseshoe magnet, refrigerator magnets

(c) Temporary Magnets

1. Lose their magnetism when removed from a magnetic field


2. Example: soft iron nail becomes magnetic when placed near a magnet

(d) Permanent Magnets

1. Retain magnetism over a long time


2. Example: bar magnets used in compasses

1. Poles – Every magnet has two poles: North and South


2. Attraction and Repulsion –
   
   
   1. Like poles repel each other (N–N or S–S)
   
   
   2. Unlike poles attract each other (N–S)
   
   


3. Magnetic Field – Area around a magnet where its force is felt. Represented by field lines


4. Magnetization – Process of making a material magnetic

1. Like poles repel, unlike poles attract


2. The magnetic force acts along the line joining the poles


3. Magnetic poles always exist in pairs; a single pole cannot exist alone

1. Magnetic materials are attracted by a magnet (e.g., iron, cobalt, nickel)


2. Non-magnetic materials are not attracted (e.g., wood, plastic, glass, copper)

1. By Stroking – Rubbing a magnetic material with one pole of a magnet in one direction


2. By Electric Current – Using an electric current through a coil to produce a magnetic field


3. By Induction – Placing a magnetic material near a magnet so it becomes temporarily magnetized


4. By Hammering in a Magnetic Field – Hammering a soft iron bar while it is in the direction of the magnetic field

Process of removing magnetism from a magnet. Methods include:

1. Heating the magnet to high temperatures


2. Hammering or striking the magnet


3. Placing the magnet in a reverse magnetic field

1. Compass – for navigation, aligns with Earth’s magnetic field


2. Electric motors and generators – convert electrical energy to mechanical energy and vice versa


3. Speakers and microphones – for sound conversion


4. Magnetic separators – separate magnetic materials from non-magnetic ones


5. Magnetic storage – e.g., hard drives, tapes

Imaginary lines that show the direction and strength of a magnetic field. Properties include:

1. Lines go from north pole to south pole outside the magnet


2. Lines are closer together where the field is strong


3. Never cross each other

1. Earth behaves like a giant magnet with a magnetic north and south pole


2. Compass needles point to the magnetic north because of Earth’s magnetic field


3. The Earth’s magnetic field protects living organisms from harmful solar radiation

1. Keep magnets away from electronic devices and magnetic storage


2. Avoid heating, hammering, or dropping magnets unnecessarily


3. Store magnets by placing opposite poles together to preserve magnetism

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CONCLUSION

1. Magnetism is an essential phenomenon in navigation, electricity generation, industrial processes, and technology


2. Understanding types, properties, laws, and uses of magnets helps in practical applications in daily life