1. Play with your magnets!

2. ALL magnets have two poles
NORTH seeking pole
SOUTH seeking pole

3. Breaking a magnet produces two magnets!

4. Opposites attract!

5. Opposite poles attract and like poles repel

6. Magnetic materials

7. Magnetic materials
Iron (steel), Cobalt and Nickel

8. Magnetic induction

9. Magnetic induction
When a magnetic material is close to a magnet, it becomes a magnet itself
We say it has induced magnetism
magnet S N N S

10. Hard and Soft Magnetism

11. Soft Magnetism Pure iron is a soft magnetic material
It is easy to magnetise but loses its magnetism easily
before
after N S S N N S N
Not a magnet
Iron nail

12. Hard Magnetism Steel is a hard magnetic material
It is harder to magnetise, but keeps its magnetism (it is used to make magnets!)
before
after S N S N N S N N
It’s a magnet! S
Steel paper clip

13. I wonder if this is a magnetic field?

14. Magnetic field
Magnets (and electric currents) produce magnetic fields around them.
In the magnetic field, another magnet or magnetic material will experience a magnetic force.

15. Magnetic field lines
We can represent the magnetic field around a magnet using field lines.

16. Magnetic field lines
The arrows show the direction a compass needle would point at that point in the field.

17. Magnetic field lines
The arrows show the direction a compass needle would point at that point in the field.
The closer the field lines are, the stronger the magnetic force felt

18. Earth’s Magnetic Field
Remember the North of a compass needle points to the geographic north pole (i.e. the geographic North pole is a magnetic south pole!) N S

19. Field around a bar magnet

20. Two bar magnets
Strong uniform field

21. Two bar magnets
no field!

22. That’s it!

23. Mind-map
Mr Porter is now going to put these slides on a loop and you’re going to mind-map them!