1. Unit 6 Magnetism
Chapter 8
Pages

2. Magnets Two magnets exert a force on each other
The magnetic force is the interaction you feel before the two magnets even touch each other
The strength of this force increases as you move the magnets closer together

3. The magnetic field exerts the magnetic force
Each magnet has a north and south pole
This is where the magnetic force is the strongest
Like poles repel
Opposite poles attract

4. Earth’s Magnetic Field
On a compass, the needle points to geographic North
This is because earth’s south magnetic pole is located in Canada
So opposites attract
The north on the compass to the “south” in Canada

5. Magnetic Domains
Groups of atoms with aligned magnetic poles are called magnetic domains
This allows the object to behave like a magnetic with a north and south pole
Ex: Placing a magnet against an iron nail will cause all the atoms to orient themselves in the same direction and temporarily cause the nail to act as a magnet

6. Electric Current and Magnetism
Moving charges produce magnetic fields
The direction of the field depends on the direction of the current
The strength of the field depends on the amount of current flowing through the wire

7. Electromagnets
An electromagnet is a temporary magnet made by placing iron inside a current carrying coil of wire
The more the wire is coiled around the iron, it causes a stronger magnetic field
When current flows through the electromagnet it moves toward or away from another magnet, converting electric energy into mechanical energy to do work
Ex: stereo speakers contain electromagnets

8. Galvanometers Gauges on your dashboard of your car are galvanometers
They measure the current being sent from sensors which in turn register the amount of ex: gasoline you have left

9. Electric Motors
An electric motor is a device that changes electrical energy into mechanical energy
Like galvanometers, electric motors use an electromagnet
The movement of the current is constantly switched back and forth to maintain the rotation of the coil
Some motors use a commutator to do this, others use household alternating current

10. Electric motors are most useful if their rotation speed is controlled
Today’s motors are smaller, more powerful, and more efficient than the first ones developed in the late 1800s

11. Electric Generators
Electromagnetic induction is caused when a magnet is moved through a wire coil or rotating a coil of wire through a magnetic field
This is how generators produce electricity
Again, the current flow must constantly switch directions in order for the coil to turn continuously

12. Types of Generators In your car, it is called an alternator
Power plants use generators to allow electricity to reach your home
Here the electromagnets are connected to a turbine pushed by either water, wind, or steam

13. Direct and Alternating Currents
A battery produces a direct current, which flows in only one direction of a wire
Generators produce alternating current, which reverses the direction of current flow in a regular way

14. Transformers
Alternating current traveling through power lines is a high voltage so as to reduce the amount of energy lost as heat
A transformer can either decrease the voltage (step down) or increase it (step up)
Step up transformers have more turns of wire in the secondary coil than in the primary coil