Spinning
In most forms of electric generation,
mechanical rotating energy is turned into electricity in coal, nuclear and
geothermal power plants, where water is heated into hot steam, which is then used
to turn a turbine---a device like a giant fan. In hydroelectric generation,
flowing water turns the turbine, and in wind power, the wind turns it. The
turbine is hooked up to a generator, which actually produces the power.
The
Generator
The generator has a rotating magnet
surrounded by coils of wire. As the magnet turns around, the direction of its
magnetic field flips from negative to positive and back again. This field
permeates the wire. When wire is permeated in this way by a moving magnetic
field, it creates a moving current in the wire. This current is called AC, or
alternating current electricity, because it changes from positive to negative
to positive continuously instead of flowing in one direction.
Step
It Up
The power is then put through a device
called a step-up transformer. When a wire coil with a changing current running
through it is put next to a coil without current running through it, the
current from the first wire produces a current in the second. If the second
coil has more turns of wire than the first, it receives a higher voltage
current than the first wire. A set of coils working this way constitute a
step-up transformer.
Cables
and Substations
Voltage needs to be stepped up because it
might have miles to travel before it gets to your house. Voltage is like
pressure---it controls how hard the electricity pushes. Electric wire is a
pretty good conductor, but it resists the flow of electricity somewhat. Having
high voltage keeps the electricity flowing efficiently without slowing down or
losing power. If the electricity has very far to go, it might pass through a
substation, where it is boosted again on the way to its destination.
Step
It Down
When the electricity gets to your house, it
is run through a step-down transformer. In the United States, this reduces it
to 120 volts, but in most other countries, the electricity comes in at 210 to
240 volts. Either way, the electricity is at a much safer level then in the
electric main. Even if you were to accidentally get an electric shock from it,
it probably wouldn't seriously injure or kill you.The electricity runs through
a power meter that records how much you use, and then into the fuse box or
circuit breaker in your house. From there, it flows into all the power outlets
and built-in appliances.
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