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Topic 6
Generators and Motors
Electricity to Magnetism
• Hans Christian
Oersted 1820 noticed
the relationship.
Electromagnets
• Soft iron core, wire
wrapped around and a
current passes through
wire creates a strong
magnet – electromagnet
• Stronger current = more
powerful magnet
• More coils = stronger
magnet
• Electricity causes the
magnetic domains to all
line up.
Magnetism to Electricity
• A magnet and a coil of wire
can produce and electric
current.
– Watch demo- electric currentgenerating tube
• This is how an electrical
generator works – it takes
mechanical energy (and
magnetism) then converts it
into electrical energy.
AC generator
• Coil of wire (armature), rotates inside
stationary field magnet – electrons are
forced to move – how do we get the
coil to move?
AC Generator cont…
• As the side of the coil passes the
opposite magnet pole, the electrons
move in the other direction creating
alternating current!
• In Canada it changes direction 120
times in a second – 60 Hertz
• AC current is handy! Can travel long
distances and we can change the
voltage easily.
Generators
• Generators in a hydroelectric power plant
DC Generators
• A Dynamo is a type of DC generator
• Current is produced in one direction only –
direct current
Motors
• Take electrical energy and change it to
mechanical energy
• Motors use energy
– (opposite to a generator – makes energy)
Building a motor video
• http://www.learnalberta.ca/content/seetb/ht
ml/movieLauncher.html?movie=video/unit_
d/lbmotor.mov
• Current going through coils creates
magnetic field which repels/attracts to
permanent magnetic field.
Parts of a DC Motor
• St. Louis Motor Demos
• Brushes – conduct electricity to
commutator
• Split Ring Commutator –
gaps stop current
• Permanent Magnets – cause
magnetic field.
• Armature – rotates due to
magnetic repulsion
• http://student.norquest.ca/online
learning/physics30/stlouismotor
/stlouismotor_frame.htm