Transcript Producing Electric Current - Broken Arrow Public Schools

Alternating and Direct Current
 Direct 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 &
Generators
 Electromagnetic 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
 Generators
 Machines that produce electric current by rotating a coil
of wire in a magnetic field
 Wire coil is wrapped around an iron core and placed
between the poles of a permanent magnet.
Generators
 Coil is rotated by an outside source of mechanical energy
 Examples: 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 Generators
 Electricity in the home comes from a power plant
with huge generators
 When 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 plant
 Electromagnets contain coils of wire wrapped around
iron cores
 Rotating magnets connect to a turbine
 Turbine: 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 Currents
 Compare and contrast current in batteries and
generators:
 Compare: Both devices move electrons through the wire
 Contrast: 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-andhydroelectric-power/
 https://www.youtube.com/watch?v=IwdtXGAtgvE#t=
59 Harnessing Waves?