Ch. 3 Sec. 3Electricity from

Magnetism

(Electromagnetic) induction

• Process of generating an electric current by moving a conductor in a magnetic field

• Produces induced current

The flow of an induced current may be constant, or

may change direction.

http://www.youtube.com/watch?v=gfJG4M4wi1o

DC• Direct Current• Charges flow in

1 direction• Used by

Thomas Edison• Type of current

found in battery

AC• Alternating Current• Charges move back & forth

in circuit• Used by Nikola Tesla• Advantage over DC-voltage

can be easily raised or lowered

• Type of current found in homes

Bill Nye The Science Guy- AC/DC Charge

• Well, everybody knowsThat when electrons flowThat flow is known as electricityAnd although you might say "So?", without it don't you knowYou'd be unplugged but not on MTVNow in a battery, current's called DCIt flows straight from the minus to the plusBut the current in your wall is known as AC, y'allAnd it cycles back and forth without a fuss.

So don't lose that charge, that AC/DC chargeYour current alternating or direct'Cause if you lose that charge, that AC/DC chargeThere's no reason for a circuit to connectOooooooh

YouTube video-Bill Nye AC DC song

http://www.youtube.com/watch?v=JZjMuIHoBeg&feature=related

http://www.youtube.com/watch?v=g17f9J1-r-k

http://www.youtube.com/watch?v=8VEg6L2QG5o&feature=related

Direct and Alternating Current

Electric generator Electric motorMechanical energy electrical energy

Electrical energy mechanical energy

DC AC

AC vs DC

TRANSFORMER• device that increases

or decreases voltage

• consists of 2 separate coils of wire wrapped around an iron core

1. primary coil2. secondary coil

primary coil

• connected to a circuit w/ a voltage source & alternating current

secondary coil

• connected to a separate circuit that does not contain a voltage source

http://www.youtube.com/watch?v=VucsoEhB0NA&feature=related

Electric current from generating plant

• AC• transmitted

@ high voltage used @ low voltage

STEP-UP TRANSFORMER

• increases voltage

STEP-DOWN TRANSFORMER

• decreases voltage

Schoolhouse Rock-Electricity