Electricity from Magnetism When you use an electric appliance or turn on a light in your home, you...

Electricity from MagnetismElectricity from Magnetism

• When you use an electric appliance When you use an electric appliance or turn on a light in your home, you or turn on a light in your home, you probably don’t think about where probably don’t think about where the energy comes from. the energy comes from.

• How does a magnetic How does a magnetic

field produce electric field produce electric

current?current?


• In 1831 Michael Faraday was able In 1831 Michael Faraday was able to generate an electric current to generate an electric current from a magnetic field.from a magnetic field.


• When a bar magnet is When a bar magnet is thrust into a coil thrust into a coil connected to an connected to an electric circuit, a electric circuit, a current is caused to current is caused to flow in the circuit to flow in the circuit to which the coil is which the coil is attached. If the magnet attached. If the magnet is withdrawn, the is withdrawn, the direction of the current direction of the current is reversed. Such is reversed. Such currents are called currents are called INDUCED CURRENTSINDUCED CURRENTS


• The size of the current The size of the current depends on how fast depends on how fast the magnet moves in the magnet moves in or out of the coil, and or out of the coil, and the number of loops in the number of loops in the coil.the coil.

• The phenomenon of The phenomenon of inducing a current by inducing a current by changing the magnetic changing the magnetic field in a coil of wire is field in a coil of wire is known as known as ELECTROMAGNETIC ELECTROMAGNETIC INDUCTIONINDUCTION..


• Faraday showed that Faraday showed that the magnetic field the magnetic field around a wire can be around a wire can be changed by moving changed by moving either the magnet in either the magnet in and out of a coil of and out of a coil of wire OR by moving a wire OR by moving a wire between the wire between the poles of a magnet.poles of a magnet.


• A generator is a device that uses A generator is a device that uses electromagnetic induction to electromagnetic induction to convert kinetic energy into convert kinetic energy into electrical energy.electrical energy.


• The electric current The electric current produced by the produced by the generator changes generator changes direction each time the direction each time the coil makes a half-turn. coil makes a half-turn. Because the electric Because the electric current continually current continually changes direction, the changes direction, the electric current is an electric current is an alternating current.alternating current.


• Another device that relies Another device that relies on electromagnetic on electromagnetic induction is a induction is a transformer. transformer.

• A transformer increases A transformer increases or decreases the voltage or decreases the voltage of an alternating current. of an alternating current.

• A simple transformer A simple transformer consists of two coils of consists of two coils of wire wrapped around an wire wrapped around an iron ring.iron ring.


• In hydroelectric plants, water flowing In hydroelectric plants, water flowing downhill turns a turbine. The downhill turns a turbine. The turbine turns the magnet of a turbine turns the magnet of a generator, inducing electric current.generator, inducing electric current.


• In nuclear power In nuclear power plants, thermal plants, thermal energy createdenergy created

by a nuclear by a nuclear reaction boils reaction boils

water to produce water to produce steam which turns steam which turns

a turbine.a turbine.


• The electric current The electric current that provides your that provides your home with electrical home with electrical energy is usually energy is usually transformed 3 times transformed 3 times before it reaches before it reaches your home.your home.


1. 1. The power plant The power plant produces electric produces electric current with high current with high voltage. To decrease voltage. To decrease the loss of power the loss of power over long distance over long distance transmission, step-up transmission, step-up transformers transformers increase the voltage increase the voltage thousands of times!thousands of times!


2. The electricity travels over transmission 2. The electricity travels over transmission lines with very high voltage to a lines with very high voltage to a distribution station with a step-down distribution station with a step-down transformer that lowers the voltage.transformer that lowers the voltage.


3. The electric 3. The electric current travels current travels over local power over local power lines to another lines to another step-down step-down transformer which transformer which lowers the voltage lowers the voltage again before the again before the current reaches current reaches your house.your house.

Electricity from Magnetism When you use an electric appliance or turn on a light in your home, you...

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