1. 2nd Year Science Ms. Shevlin
Chapter 41 Magnetism
2nd Year Science
Ms. Shevlin

2. Objectives:
To discuss what magnetism is
To investigate how magnetic forces work
To examine how magnets work
To carry out an experiment to show the magnetic field around a bar magnet using iron filings and plotting compasses
To discuss places where magnets are used in everyday life

3. A magnet is a piece of metal that can attract other substances to it.
Magnets were first discovered about 2,500 years ago.
Man-made Magnets
Only three magnets from the periodical table can be magnetised e.g. iron, nickel & cobalt.
Strong magnets can be made by mixing elements to form alloys e.g. steel = carbon + iron
Alnico = aluminium + nickel + iron + cobalt

4. What is magnetism?
Magnetism is a FORCE.

5. How do magnetic forces act?
Magnetic forces can be attractive or repulsive
Like poles repel.
Unlike poles attract.

6. Where do we use magnets?
The simplest use of magnets is in the compass.
When a magnet is free to move it lines up north-south.
This happens because the earth is a giant magnet.

7. Can you make a compass?
These are two easy ways to make your own compass.
Give one a try but remember you must magnetise your needle first.

8. Are all materials magnetic?
Three metals are attracted to magnets and can be made into magnets themselves.
These metals are iron, cobalt and nickel.
Other metals that are mixtures of these metals or alloys are also attracted to magnets.
Find out which materials you have contain one or more of these metals.

9. What is a magnetic field?
As we bring two like poles of a magnet close together we can  feel the magnets pushing away from each other.
The magnetic force acts around the magnet.
The area around the magnet where we can detect a magnetic force is called the magnetic field.

10. Does the earth have a magnetic field?
Since the earth is a giant magnet it also has a magnetic field.

11. What do I know about magnets?
Magnetism is a force. 
Magnets have two poles a north and a south.
Like poles repel.
Unlike poles attract. 
When magnets are free to move they line up north-south.
 Magnets are made from or contain iron, cobalt and nickel.
The area in which a magnetic force can be detected is called the magnetic field.