Download Electricity and magnetism connection

Electricity and magnetism
connection
History
In 1820 Hans Christian Oersted
discovered electricity passing through
a wire created a magnetic field
 However the only way to create an
electric current at the time was
reacting expensive materials
(forerunner to a modern battery)
 This is completely impractical to
provide electricity on a large scale

Discovery
A moving magnetic field can also
create and electric current
 This was discovered separately and
simultaneously by Michael Faraday
in Great Britain and Joseph Henry in
America in 1831.
 Both moved a coil of wire over a
magnet and saw a current was
created, and the current created a
magnetic field.

Electromagnetic Induction
~ the creation of a magnetic field by
electric current or the creation of an
electric current by a magnetic field.
 The amount of voltage depends on
how quickly either the magnet or
wire is moving.
 Faster motion means a higher
voltage will be created.

Faraday’s Law
~The induced voltage in a coil is
proportional to the product of the
number of loops in a wire
 The voltage also depends upon the
number of loops it is passing
through

Eddy Current
Moving a magnetic field through a
conductor shaped in a cylinder. (or
vice versa)
 causes a circulating flow of current
(eddy)
 The resistance in the conductor causes
a dragging effect (like friction) slowing
the magnet down.
 These are used as breaking systems at
the end of some roller coasters

Eddy Forces
Generators
Generators produce electricity by
spinning a coil of wire in front of
permanent magnets.
 Since it keeps going back and forth
it produces an alternating current.
 If you want a DC current you have
to use a commutator (works the
same as the stuff in a DC motor).

Alternating Current
Remember alternating current
simply sway back and forth
 They don’t move through
(constantly in one direction) a wire
 The electrons have a net movement
forward, then backward (repeat)
 This is why alternating current
generators in a car is called an
alternator

Generator
DC generator
in action
AC generator
in action
Generators
The shaft of the loop of wires is
connected to a turbine.
 The goal of all electric power plants
is to get a turbine to spin.
 By spinning this turbine we can
convert mechanical (kinetic) energy
to electromagnetic energy.

Types of power plants
Hydroelectric- put a turbine in a
river or water fall and let the water
spin the turbine.
 Coal- burn coal to boil water, steam
rises and spins a turbine.
 Nuclear- same as coal but use a
nuclear fission to boil water.

Hydroplant
Coal Plant
Nuclear power plant
homework
Pg 758
 1-10
