Alternating and Direct CurrentDirect Current (DC) is the one way flow of electrical

charge from a positive to a negative charge. Batteries produce direct current.Direct Current is different than alternating current

because the charge only flows in one direction.Alternating Current (AC) is when charges

flow back and forth from a source.It is the way we receive our electricity (for our

houses, businesses, etc.)The purpose of transformers is to convert AC

voltages.Transformers are extremely important to AC

current, and our life.

From Mechanical to Electrical Energy

A magnet can produce an electric current-Moving a loop of wire through a magnetic

field causes electric current to flow in the wire

Moving a magnet through a loop of wire has the same effect

How can a magnet produce a current in a wire? Due to the motion of the wire or magnet is

converted to electrical energy

Electromagnetic induction & GeneratorsElectromagnetic Induction

Producing an electric current by moving a loop of wire through a magnetic field or moving a magnet through a wire loop

http://www.youtube.com/watch?v=uoQelu7XRjk

GeneratorsMachines that produce electric current by

rotating a coil of wire in a magnetic fieldWire coil is wrapped around an iron core and

placed between the poles of a permanent magnet.

GeneratorsCoil is rotated by an outside source of mechanical

energyExamples: Steam, wind, water

As the coil turns in the magnetic field, electric current flows through the wire

When the coil turns so that the ends move past opposite ends of the magnet: The current reverses direction

The current changes direction twice with each revolution

A generator that is used in a car is known as an alternator

Electric GeneratorsElectricity in the home comes from a power

plant with huge generatorsWhen the coil is fixed and the magnet

rotates, the current is the same as if the coil rotates and the magnet is fixed.

Construction of a generator in a power plantElectromagnets contain coils of wire wrapped

around iron coresRotating magnets connect to a turbineTurbine: large wheel that rotates due to

Brain POP Sources of electricity: http://www.teachersdomain.org/resources/phy03/sci/phys/energy/energysource/

index.html

Direct and Alternating CurrentsCompare and contrast current in batteries

and generators: Compare: Both devices move electrons through

the wireContrast: Batteries have DC. Generators have AC.

DC- Direct Current- Flows in only one direction.

AC- Alternating current- reverses the direction of current flow regularly.

In N America, generators produce alternating current at a frequency of 60 cycles per second, or 60 Hz

A 60-Hz alternating current changes direction 120 times per second

http://www.pbslearningmedia.org/resource/phy03.sci.phys.energy.hooverelec/hoover-dam-and-hydroelectric-power/

https://www.youtube.com/watch?v=IwdtXGAtgvE#t=59 Harnessing Waves?