MAGNETISM

ObjectivesBy the end of the lesson, the learner should be able to:i) Define a magnet ii) State the properties of magnetsiii) State and draw the types of magnets

Definition• A magnet is a substance (piece of metal or

other material) which is able to attract other substances.

• Magnetic materials are the ones that are attracted by a magnet

Properties of magnets

1) Presence of magnetic poles Magnets have two defined poles.North pole

and south pole.The forces of attraction are concentrated at the poles.A horse shoe magnet has its poles at the free ends.

2) Directional property When a bar magnet is suspended so that it can

freely swing around, it moves to and fro for some time and then comes to rest in a North-South direction.

Identification of the poles of a magnet

• To identify the poles of a magnet, the ends are usually painted in different colours.

• In some cases the North pole is painted red while the South pole is painted white or blue.

• In other cases, the whole bar is painted red with a white dot or spot on one end to identify the north pole.

Types of magnets

Magnets are named according to their shapes as shown below;

• U shaped magnet

Ring magnet

Horse shoe magnet

• Ceramic magnet/ magnadur magnet.

It is the most powerful magnet even when the Size is very small

Bar magnet

Magnetic and non-magnetic materials

• Magnetic materials are the ones that are attracted by magnets such as cobalt and steel

• Non-magnetic materials are the ones that cannot be attracted by a magnetic such as copper, wood, plastics e.t.c

Assignment

• State the main difference between ceramic and a bar magnet of the same size

• Draw a u- shaped magnet and a horse shoe magnet