Electricity is a form of energy. Electricity is the flow
of electrons. All matter is made up of atoms, and an atom
has a centre, called a nucleus. The nucleus contains positively
charged particles called protons and uncharged particles called
neutrons. The nucleus of an atom is surrounded by negatively
charged particles called electrons. The negative charge of
an electron is equal to the positive charge of a proton, and
the number of electrons in an atom is usually equal to the
number of protons. When the balancing force between protons
and electrons is upset by an outside force, an atom may gain
or lose an electron. When electrons are "lost" from an atom,
the free movement of these electrons constitutes an electric
current.
Electricity
is a basic part of nature and it is one of our most widely
used forms of energy. We get electricity, which is a secondary
energy source, from the conversion of other sources of energy,
like coal, natural gas, oil, nuclear power and other natural
sources, which are called primary sources. Many cities and
towns were built alongside waterfalls (a primary source
of mechanical energy) that turned water wheels to perform
work. Before electricity generation began slightly over
100 years ago, houses were lit with kerosene lamps, food
was cooled in iceboxes, and rooms were warmed by wood-burning
or coal-burning stoves. Beginning with Benjamin Franklin's
experiment with a kite one stormy night in Philadelphia,
the principles of electricity gradually became understood.
In the mid-1800s, everyone's life changed with the invention
of the electric light bulb. Prior to 1879, electricity had
been used in arc lights for outdoor lighting. The lightbulb's
invention used electricity to bring indoor lighting to our
homes.
Theory
An electric generator is a device for converting mechanical
energy into electrical energy. The process is based on the
relationship between magnetism and electricity. When a wire
or any other electrically conductive material moves across
a magnetic field, an electric current occurs in the wire.
The large generators used by the electric utility industry
have a stationary conductor. A magnet attached to the end
of a rotating shaft is positioned inside a stationary conducting
ring that is wrapped with a long, continuous piece of wire.
When the magnet rotates, it induces a small electric current
in each section of wire as it passes. Each section of wire
constitutes a small, separate electric conductor. All the
small currents of individual sections add up to one current
of considerable size. This current is what is used for electric
power.
An
electric utility power station uses either a turbine, engine,
water wheel, or other similar machine to drive an electric
generator or a device that converts mechanical or chemical
energy to electricity. Steam turbines, internal-combustion
engines, gas combustion turbines, water turbines, and wind
turbines are the most common methods to generate electricity.
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