1. Based on the magnetic field alone what could this image be?

2. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.

3. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
What’s Wrong?
Field lines should exit at the North Pole

4. Where does the Earth’s magnetism come from?
Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Where does the Earth’s magnetism come from?

5. Electrical current + Movement = Magnetic Field
Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Magnetic fields in the inner core interact with the moving fluid iron in the outer core and produce small electrical currents.
Electrical current + Movement = Magnetic Field
“Self exciting dynamo” or a “geo-dynamo”

6. How things work… How does a compass work?
Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
How things work…
How does a compass work?

7. How things work… North Attract Vacuum Poles Align Iron Magnetic Field
Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
How things work…
Explain how a compass can be used to find the magnetic North of Earth. Your answer should include reference to the materials involved (6 marks)
North
Attract
Poles
Vacuum
Align
Iron
Magnetic Field

8. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
How things work…
Why when I hold a compass near to a metal object why does it stop pointing North?

10. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Domains and Magnets
Magnetic materials are made of domains, small magnetic regions. When these domains align (right) the material will produce a large magnetic field. When they do not align (left) the domains cancel out and no magnetic field is created.

11. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Demagnetising
Hitting a magnet with a hammer or similar will throw all the domains out of line and therefore demagnetise the metal.
Heating to a high temperature has a similar effect.

12. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Making a Magnet
Stroking an iron bar with a magnet will magnetise it. The stroking action aligns the “domains” forcing them all to point in the same direction.

13. Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Induced Magnetism
Other materials can also have magnetism “induced”. Think of paper clips or pins, they will still be attracted to a magnet if placed within a magnetic field but wouldn’t normally have a magnetic field themselves. In this situation they act as a magnet, but only whilst in the magnetic field. This is called induced magnetism.

14. Testing magnets Follow these simple rules for testing magnets…
Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Testing magnets
Follow these simple rules for testing magnets…
Objects that are made of unmagnetised iron, cobalt and nickel are attracted to either pole of a magnet, but never repelled.
Objects which are not attracted to either pole are not magnetic
You can only show that an object is a magnet if it repels another magnet.

16. Now complete the questions 
Specification Aims By the end of this lesson you should be able to…
Distinguish between permanent magnetism and induced magnetism.
Describe how a compass works including details of the Earth’s magnetic field.
Solve problems using the magnetic field lines around magnets as a guide.
Now complete the questions 