1. Chapter 8 Section 3--Magnetism

2. From Mechanical to Electrical Energy
Michael Faraday and Joseph Henry (in US
Discovered moving a loop of wire through a magnetic field causes an electric current to flow in the wire
Electromagnetic induction:
producing a current by moving a loop of wire through a magnetic field (or vice versa)

3. Generators:
Generator: a generator produces electric current by rotating a coil of wire in a magnetic field
Most of electricity you use each day is produced by generators using electromagnetic induction

4. Switching Directions A generator’s coil rotates
Current flows through the coil
Current flow direction must switch periodically to keep electromagnetic coil turning
In US—generators rotate 60 X /sec OR 3,700 rpm’s

5. Using Electric Generators
1 type of generator—alternator in cars
Alternators: provide electrical energy to operate lights, etc.
Spark plugs also use electricity to ignite fuel in engine’s cylinders
Once car is running, mech. Energy turns coil in alternator

6. Generating Electricity for your home
Your electricity comes from a power plant with huge generators
Electromagnets in these generators have coils of wire wrapped around iron cores
Turbine—rotating magnets in generators are connected to turbines-wheels that rotate when pushed by water, wind or steam

7. Direct and Alternating Currents
Batteries produce—Direct Current (DC)
Flows in one direction through a wire
Alternating Current (AC)—reverses the direction of the current flow in a regular way
*in US—at rate of 60 cycles/sec

8. Transformers:
Transformer: a device that increases or decreases the voltage of an alternating current
Made of two coils of wire called primary and secondary coils

9. More about transformers:
Step-up transforms: if 2ndary coil in a transformer has more turns of wire than the primary coil does—steps up
Step-down transformers: a transformer that reduces voltage/the number of turns in the secondary coil is less than the number of turns in the primary coil