1. Magnetism
Electric Motors
Computer Disc Drives
Alarm Systems

2. Electricity and Magnetism
What is the difference between MAGNET and MAGNETIC?

3. Properties of Magnets Magnets have two opposite poles.
north
south
Magnets exert forces on each other.
The forces depend on the alignment of the poles.

4. Magnetism works because the magnetic force is greater than the gravitational force.
Magnetic Field
Magnetic forces exist in what we call a “magnetic field”.

5. The number of field lines indicates the strength of the source of the magnet.
Every magnet creates an energy
field
The field exerts forces on any
other magnet that is within its
range.

7. Magnetic lines of force NEVER cross.
Unlike poles of magnets attract each other and like poles of magnets repel.
Magnetic lines of force NEVER cross.
Two or more magnetic fields overlapping COMBINE.

8. The earth is like a giant magnet!
The nickel iron core of the earth gives the earth a magnetic field much like a bar magnet.

9. Types of Magnets Temporary Magnets ~These magnets tend to lose
their magnetism after a while
EX: Some refrigerator magnets
when dropped again and again
will no longer be attracted to
metal.

10. Types of Magnets Electromagnets
~Created when there is electric current flowing through a coil of wire wrapped around a magnet or metal core.

11. Permanent Magnets Natural Magnets
Keep their magnetism.
A mixture of iron, aluminum, nickel, & cobalt.
Permanent Magnets
Found in nature.
Example: lodestone-used in compasses.
Natural Magnets

12. Electricity and Magnetism – how are they related?
When an electric current passes through a wire a magnetic field is formed.

13. What is electromagnetic induction?
Moving a loop of wire through a magnetic field produces an electric current. This is electromagnetic induction.
A generator is used to convert mechanical energy into electrical energy by electromagnetic induction.

14. Electromagnetic Induction
Process by which a current is produced by a changing magnetic field.
By either moving the magnet or the wire, electricity is produced.
Ex: Generators-used to convert mechanical energy into electrical energy by electromagnetic induction.
Electromagnetic Induction

15. Generating Electricity
A power plant generator contains a turbine that turns magnets inside loops of wire to generate electricity.
Generating Electricity

17. What are electric motors?
An electric motor is a device which changes electrical energy into mechanical energy.

18. MAGLEV TRAINS!!

19. Vocabulary!!
Electric current Electromagnet Electromagnetism Generator Induction Magnetic field Magnetic force Motor