Before electricity became
available over 100 years ago, houses were lit with kerosene lamps, food
was cooled in iceboxes, and rooms were warmed by wood-burning or
Many scientists and
inventors have worked to decipher the principles of electricity since the
1600s. Some notable accomplishments were made by Benjamin Franklin, Thomas
Edison, and Nikola Tesla.
demonstrated that lightning is electricity. Thomas Edison invented the
first long-lasting incandescent light bulb.
Prior to 1879, direct
current (DC) electricity had been used in arc lights for outdoor lighting.
In the late 1800s, Nikola Tesla pioneered the generation, transmission,
and use of alternating current (AC) electricity, which reduced the cost of
transmitting electricity over long distances. Tesla's inventions used
electricity to bring indoor lighting to our homes and to power industrial
Electrons, electricity, electronic and other words that begin with "electr..."
all originate from the Greek word "elektor," meaning "beaming sun." In Greek,
"elektron" is the word for amber.
Amber is a very pretty goldish brown "stone" that sparkles orange and
yellow in sunlight. Amber is actually fossilized tree sap! It's the stuff
used in the movie "Jurassic Park." Millions of years ago insects got stuck
in the tree sap. Small insects which had bitten the dinosaurs, had blood
with DNA from the dinosaurs in the insect's bodies, which were now
fossilized in the amber. Ancient Greeks discovered that amber behaved
oddly - like attracting feathers - when rubbed by fur or other objects.
They didn't know what it was that caused this phenomenon. But the Greeks
had discovered one of the first examples of static electricity . The Latin
word, electricus, means to "produce from amber by friction." So, we get
our English word electricity from Greek and Latin words that were about
Electricity is an apparent force in nature that exists whenever there is
a net electrical charge between any two objects.
Electricity is a form of energy produced by the movement of electrons.
All matter is made
up of atoms, and atoms are made up of smaller particles. The three main
particles making up an atom are the proton, the neutron and the electron.
Electrons spin around the center, or nucleus, of atoms, in the same way the moon
spins around the earth. The nucleus is made up of neutrons and protons.
Electrons contain a
negative charge, protons a positive charge. Neutrons are neutral -- they have
neither a positive nor a negative charge.
Each atom has a
specific number of electrons, protons and neutrons. But no matter how many
particles an atom has, the number of electrons usually needs to be the same as
the number of protons. If the numbers are the same, the atom is called balanced,
and it is very stable.
So, if an atom had
six protons, it should also have six electrons. The element with six protons and
six electrons is called carbon. Carbon is found in abundance in the sun, stars,
comets, atmospheres of most planets, and the food we eat. Coal is made of
carbon; so are diamonds
Some kinds of atoms
have loosely attached electrons. An atom that loses electrons has more protons
than electrons and is positively charged. An atom that gains electrons has more
negative particles and is negatively charge. A "charged" atom is called an
Electrons can be made to move from one atom to another. When those electrons
move between the atoms, a current of electricity is created. The electrons move
from one atom to another in a "flow." One electron is attached and another
electron is lost.
Since all atoms want
to be balanced, the atom that has been "unbalanced" will look for a free
electron to fill the place of the missing one. We say that this unbalanced atom
has a "positive charge" (+) because it has too many protons.
Since it got kicked
off, the free electron moves around waiting for an unbalanced atom to give it a
home. The free electron charge is negative, and has no proton to balance it out,
so we say that it has a "negative charge" (-).
engineers have found several ways to create large numbers of positive atoms and
free negative electrons. Since positive atoms want negative electrons so they
can be balanced, they have a strong attraction for the electrons. The electrons
also want to be part of a balanced atom, so they have a strong attraction to the
positive atoms. So, the positive attracts the negative to balance out.
The more positive
atoms or negative electrons you have, the stronger the attraction for the other.
Since we have both positive and negative charged groups attracted to each other,
we call the total attraction "charge."
When electrons move
among the atoms of matter, a current of electricity is created. This is what
happens in a piece of wire. The electrons are passed from atom to atom, creating
an electrical current from one end to other.
conducted through some things better than others do. Its resistance measures how
well something conducts electricity. Some things hold their electrons very
tightly. Electrons do not move through them very well. These things are called
insulators. Rubber, plastic, cloth, glass and dry air are good insulators and
have very high resistance.
Other materials have
some loosely held electrons, which move through them very easily. These are
called conductors. Most metals -- like copper, aluminum or steel -- are good
Electricity is the flow of electrical power or charge. It is a secondary
energy source which means that we get it from the conversion of other
sources of energy, like coal, natural gas, oil, nuclear power and other
natural sources, which are called primary sources. The energy sources we
use to make electricity can be renewable or non-renewable, but electricity
itself is neither renewable or non-renewable.
There are two kinds of electricity: static electricity and current
Static electricity stays in one place and doesn't move like current electricity.
Lightning is the most spectacular example of static electricity. This is a huge
spark that flows between positive charges in the top of a thunder cloud and
negative charges in the bottom.
Current electricity is the flow of electric charge through a substance
that conducts electricity. Volts, amps, and watts measure
electricity. Volts measure the "pressure" under which electricity flows.
Amps measure the amount of electric current. Watts measure the amount of
work done by a certain amount of current at a certain pressure or voltage,
it was named to honor James Watt, the inventor of the steam engine.
Current is a measure of the rate of electron flow through a material.
Electrical current is measured in units of amperes or "amps" for short.
This flow of electrical current develops when electrons are forced from
one atom to another.
Ampere - a measure of current -One amp is defined as 6.28 x 10 18
electrons per second.
Volt - A volt is a measurement of electromotive force in electricity.
This is the electric force that "pushes" electrons around a circuit.
"Volt" is named after Alessandro Volta, an Italian physicist who
invented the first battery.
Watt - a measure of the power of electricity
Kilowatt-hour - a measure of electric energy
Electrical power is usually measured in watt (W), kilowatt (kW),
describe the rate at which electricity is being used at a specific
moment. For example, 100 watts describes the amount of electricity that
a 100-watt light bulb draws at any particular moment.
Watt-hours measure the total amount of electricity used over time.
Watt-hours are a combination of the how fast the electricity is used
(watts) and the length of time it is used (hours). For example, a
100-watt light bulb, which draws 100 watts at any one moment, uses 100
watt-hours of electricity in the course of one hour.
and kilowatt-hours are useful for measuring amounts of electricity
used by large appliances, such as refrigerators, and by households.
Kilowatt-hours are what show up on your electricity bill. One kilowatt
(kW) equals 1,000 watts, and one kilowatt-hour (kWh) is one hour of
using electricity at a rate of 1,000 watts. New, energy-efficient
refrigerators use about 1.4 kilowatt-hours per day, and about 500
kilowatt-hours per year.
are used to measure the output of a power plant or the amount of
electricity required by an entire city. One megawatt (MW) = 1,000
kilowatts = 1,000,000 watts. The average size of US power plants is 213
MW. A 1000 MW power plant is a large plant.
measure the capacity of large power plants or of many plants. One
gigawatt (GW) = 1,000 megawatts = 1 billion watts. In 1990, if all US
electrical generating plants were operating at full capacity at the same
time, they would have produced 690 GW.
Electricity generation - whether from fossil fuels, nuclear, renewable
fuels, or other sources - is usually* based on the fact that "When magnets
are moved near a wire, an electric current is generated in that wire."
Electricity generation - whether from fossil fuels, nuclear , renewable
fuels, or other sources - is usually* based on the fact that:
"When magnets are moved near a wire, an electric current is generated in
Batteries Produce Electricity
Credit: Northwestern University
A battery produces electricity using two different metals in a chemical
solution. A chemical reaction between the metals and the chemicals frees
more electrons in one metal than in the other. One end of the battery is
attached to one of the metals; the other end is attached to the other
The end that
frees more electrons develops a positive charge and the other end develops
a negative charge. If a wire is attached from one end of the battery to
the other, electrons flow through the wire to balance the electrical
A load is a
device that does work or performs a job. If a load –– such as a light bulb
–– is placed along the wire, the electricity can do work as it flows
through the wire. Electrons flow from the negative end of the battery
through the wire to the light bulb. The electricity flows through the wire
in the light bulb and back to the positive end of the battery.
Electricity Travels in Circuits
Electricity travels in closed loops, or circuits. It must have a complete
path before the electrons can move. If a circuit is open, the electrons
cannot flow. When we flip on a light switch, we close a circuit. The
electricity flows from an electric wire, through the light bulb, and back
out another wire.
When we flip
the switch off, we open the circuit. No electricity flows to the light.
When we turn a light switch on, electricity flows through a tiny wire in
the bulb. The wire gets very hot. It makes the gas in the bulb glow. When
the bulb burns out, the tiny wire has broken. The path through the bulb is
Conventional electricity sources include coal, nuclear, oil, natural gas,
and large hydropower facilities. These sources supply about 99% of the
electricity used in the United States today.
In a power plant, electricity is produced by generators, which are driven
by turbines. Turbines may be powered by water, as in a hydroelectric
plant, by wind, or by steam, as in a nuclear or fossil fuel plant.
The generator is based on the principle of "electromagnetic induction"
discovered in 1831 by Michael Faraday, a British scientist. Faraday
discovered that if an electric conductor, like a copper wire, is moved
through a magnetic field, electric current will flow (or "be induced") in
the conductor. So the mechanical energy of the moving wire is converted
into the electric energy of the current that flows in the wire.
California Energy Commission Graphic
The boiler in a power plant has two basic functions: to burn fuel to
produce heat and to use the heat to turn water into steam.Fuel enters the boiler's furnace and is ignited, producing
walls of the boiler are long, vertical tubes that contain water.As the temperature inside the boiler increases, the water
begins to boil, forming tiny steam bubbles.The steam rises to the top of the boiler to a steam collection
drum.From there, the
steam travels through pipes to the turbine.
The turbine transforms the thermal energy in the steam into mechanical
energy.It provides the
mechanical motion necessary for the generator to do its job.A turbine is constructed of a long shaft to which a series of
blades are attached.This
is called the rotor.As
steam enters the turbine, it is directed through the sets of blades.The force of the steam against the blades causes the rotor to
spin.It is similar to
blowing on a pinwheel, but much faster.Steam turbines spin at 3,600 revolutions per minute (60 cycles
per second or 60 Hz).
The generator is directly connected to the turbine, so when the
turbine spins, the generator also spins.It transforms the mechanical energy (provided by the spinning
turbine) into electrical energy.Electricity is produced by rotating a conductor through a
magnetic field or by rotating a magnetic field around the conductor.Each time the conductor travels, or cuts, through the magnetic
field, a voltage is created (induced).After leaving the generator, the electricity travels to the
plant's substation where transformers are located.The transformer increases the voltage of the electricity so it
can travel through the distribution lines efficiently.Then, in local areas, the electricity travels to another
substation where transformers reduce the voltage again for consumer
use.All this happens at
the speed of light.
After electricity is produced at power plants it has to get to the
customers that use the electricity. Our cities, towns, states and the
entire world are criss-crossed with power lines that "carry" the
When electricity leaves a power plant (1), its voltage is increased at a
“step-up” substation (2). Next, the
energy travels along a transmission line to the area where the power is
needed (3). Once there, the voltage is
decreased or “stepped-down,” at another substation (4), and a distribution
power line (5) carries the
electricity until it reaches a home or business (6).
To solve the problem of sending electricity over long distances, William
Stanley developed a device called a transformer. The transformer allowed
electricity to be efficiently transmitted over long distances. This made
it possible to supply electricity to homes and businesses located far from
the electric generating plant.
Credit: Health Protection Agency UK
The electricity first goes to a transformer at the power plant that boosts the
voltage up to 400,000 volts. When electricity travels long distances it is
better to have it at higher voltages. Another way of saying this is that
electricity can be transferred more efficiently at high voltages.
The long thick cables of transmission lines are made of copper or aluminum
because they have a low resistance. Some of the electrical energy is lost
because it is changed into heat energy. High voltage transmission lines carry
electricity long distances to a substation.
Energy flow through a typical substation
The power lines go into substations near businesses, factories and homes. Here
transformers change the very high voltage electricity back into lower voltage
substations , electricity in different power levels is used to run factories,
streetcars and mass transit, light street lights and stop lights, and is sent to
In your neighborhood, another small transformer mounted on pole or in a
utility box converts the power to even lower levels to be used in your house.
The voltage is eventually reduced to 220 volts for larger appliances, like
stoves and clothes dryers, and 110 volts for lights, TVs and other smaller
Rather than over-head lines, some new distribution lines are underground. The
power lines are protected from the weather, which can cause line to break.
How Electricity Gets To
It's always there whenever you flip a
switch or plug in a cord - but electricity has to travel a long way to reach
After the generator
produces the electrical charge, the current is sent through a
transformer to make it the right voltage. This gives the electricity
enough pressure to travel long distances.
transmission lines carry the electricity over hundreds of miles to
your city or neighborhood.
It reaches a
substation, where the voltage is lowered to make it safe for
The electricity travels
through smaller distribution lines to your street.
The power passes through
a service drop and into the outdoor electric meter.
From there, it reaches
the service panel, where it branches off into separate circuits
for each area of your home.
All the distribution lines throughout the country are interconnected.This enables the utility companies to form "power pools" so that
electricity can be distributed where it is needed, which means a power
plant may, or may not, be supplying power to a local area.
Electricity is a basic part of nature and it is one of our most widely
used forms of energy.
Long before any knowledge of
electricity existed people were aware of shocks from electric fish.
Ancient Egyptian texts dating from 2750 BC referred to these fish as the
"Thunderer of the Nile", and described them as the "protectors" of all
other fish. Electric fish were again reported millennia later by ancient
Greek, Roman and Arabic naturalists and physicians.
Possibly the earliest and nearest
approach to the discovery of the identity of lightning, and electricity
from any other source, is to be attributed to the Arabs, who before the
15th century had the Arabic word for lightning (raad) applied to the
Ancient cultures around the
Mediterranean knew that certain objects, such as rods of amber, could be
rubbed with cat's fur to attract light objects like feathers. Thales of
Miletos made a series of observations on static electricity around 600 BC,
from which he believed that friction rendered amber magnetic, in contrast
to minerals such as magnetite, which needed no rubbing. Thales was
incorrect in believing the attraction was due to a magnetic effect, but
later science would prove a link between magnetism and electricity.
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
In the late-1800s, Nikola Tesla pioneered the generation, transmission,
and use of alternating current (AC) electricity, which can be transmitted
over much greater distances than direct current.
Tesla's inventions used electricity to bring indoor lighting to our homes
and to power industrial machines.
Thomas Edison helped change everyone's life -- he perfected his invention
-- the electric light bulb.
Prior to 1879, direct current (DC) electricity had been used in arc
lights for outdoor lighting.
Thales, a Greek,
found that when amber was rubbed with silk, it became
electrically charged and attracted objects. He had originally
discovered static electricity.
(England) first coined the term electricity from
the Greek word for amber. Gilbert wrote about the
electrification of many substances. He was also the first person
to use the terms electric force, magnetic pole,
and electric attraction.
Guericke (Germany) described and demonstrated a vacuum, and then
invented a machine that produced static electricity.
(Ireland) discovered that electric force could be transmitted
through a vacuum and observed attraction and repulsion.
(England) distinguished between conductors and nonconductors of
Georg Von Kleist
(Germany) developed the first electric capacitator, a device for
Musschenbroek (the Netherlands) independently developed an
electric capacitator that would be called the Leyden jar after
the University of Leyden where he worked.
(United States) tied a key to a kite string during a
thunderstorm, and proved that static electricity and lightning
were the same thing.
(Italy) invented the first electric battery. The term volt
is named in his honor.
Sir Humphry Davy
(England) invented the first effective lamp. The arc
lamp was a piece of carbon that glowed when connected by wires
to a battery.
experiments by Hans Christian Oersted (Denmark), Andre-Marie
Ampere (France), and Francois Arago (France) confirmed the
relationship between electricity and magnetism.
(England) discovered the principle of electro-magnetic rotation
that would later be the key to developing the electric motor.
(Germany) defined the relationship between power, voltage,
current and resistance in Ohms Law.
invention the induction ring, Michael Faraday
9England) proved that electricity can be induced (made) by
changes in an electromagnetic field. Faraday's experiments about
how electric current works led to the understanding of
electrical transformers and motors.
(United States) separately discovered the principle of
electromagnetic induction but did not publish his work. He also
described an electric motor.
principles, Hippolyte Pixii (France) built the first dynamo,
an electric generator capable of delivering power for
industry. Pixii's dynamo used a crank to rotate a magnet around
a piece of iron wrapped with wire.
(United States) invented the electrical relay, which could send
electrical currents long distances.
(United States) invented the electric motor, an invention that
is used in most electrical appliances today.
Robert Grove (Scotland) developed the first fuel cell, a device
that produces electrical energy by combining hydrogen and
Joule (England) showed that energy is conserved in electrical
circuits involving current flow, thermal heating, and chemical
transformations. A unit of thermal energy, the Joule, was named
(United States) invented the electric telegraph, a machine that
could send messages long distances across wires.
theory of electromagnetic fields was published.J.C. Maxwell(Scotland) created a new era of physics when he unified
magnetism, electricity, and light. Maxwell's four laws of
electrodynamics (Maxwell's Equations) eventually led to electric
power, radios, and television.
(United States) invented the open coil dynamo (or generator)
that could produce a steady current of electricity.
(England) invented the first incandescent lightbulb (also called
an electric lamp). His lightbulb burned out quickly.
(United States) developed an arc lamp that could be powered by a
(United States) founded the Edison Electric Light Co. in New
York City. He bought a number of patents related to electric
lighting and began experiments to develop a practical,
long-lasting light bulb.
experiments, Thomas Edison (United States) invented an
incandescent light bulb that could be used for about 40 hours
without burning out. By 1880, his bulbs could be used for 1,200
(Brush arc lamps) were first used for public street lighting in
Electric Light Company, Inc. in San Fransicso was the first
electric company to sell electricity to customers. The company
used two small Brush generators to power 21 Brush arc light
streetcar was invented by E.W. v. Siemens.
Edison(United States) opened the Pearl Street power station in
New York City. The power station was one of the world's first
central electric power plants and could power 5,000 lights. It
used a direct current (DC) power system, unlike the power
systems that we use today which use alternating current (AC).
hydroelectric station opened in Wisconsin.
first put electric lights on a Christmas tree.
(U.S. immigrant from Austrian Empire) invented the Tesla coil, a
transformer that changed electricity from low voltage to high
voltage, making it easier to transport over long distances.
invented the electric alternator for producing alternating
current (AC). Until this time, electricity had been generated
using direct current (DC) from batteries.
Algernon Parsons (England) invented a steam turbine generator,
capable of generating huge amounts of electricity.
Jr. (United States) developed the induction coil transformer and
an alternating current electric system.
(U.S. immigrant from Austrian Empire) demonstrated the first
polyphase alternating current (AC) electrical system. His
AC system included all units needed for electricity production
and use: generator, transformers, transmission system, motor
(used in appliances) and lights. George Westinghouse, the head
of Westinghouse Electric Company, bought the patent rights to
the AC system.
(United States) was the first to use a large windmill to
generate electricity. He used the windmill to charge batteries
in the cellar of his home in Cleveland, Ohio.
Electric Company used an alternating current (AC) system to
light the Chicago World's Fair.
A 22-mile AC
powerline was opened, sending electricity from Folsom Powerhouse
in California to Sacramento.
Falls hydropower station opened. It originally provided
electricity to the local area. One year later, when a new
alternating current (AC) powerline was opened, electric power
from Niagara Falls was sent to customers over 20 miles away in
Buffalo, New York.
Thomson (England) discovered the electron.
The first power
line between the United States and Canada was opened at Niagara
first all turbine station opened in Chicago.
largest generator (5,000 watts) was opened at Shawinigan Water
& Power; and the world's largest and highest voltage line (136
kilometers and 50 kilovolts) brought power to Montreal.
(United States) invented the first electric vacuum cleaner.
first pumped storage plant opened in Switzerland.
(United States) invented electric air conditioning.
Murray (United States) created the first air pollution control
device, the cinder catcher.
A. Goss invented
the electric refrigerator.
was invented by scientists at Bell Telephone Laboratories.
American farms had electricity.
(Canada) discovered that if a heart stopped beating owing to to
cooling, it could be started again by artificial stimulation
using mechanical or electric means. This lead to his invention
of the world's first cardiac pacemaker.
The world' s
first nuclear power plant (Russia) started generating
Energy Act of 1954 was passed. It allowed private ownership of
and Pearson (United States) working for Bell Labs, invented the
first solar cell.
reactor in Pennsylvania was the first nuclear power plant to
provide electricity to customers in the United States.
commercially available integrated circuits were produced by the
Fairchild Semiconductor Corporation (United States). All
computer manufacturers started using chips instead of the
individual transistors and their accompanying parts.
electronic desktop calculators were the ANITA Mk VII and Mk 8,
which used vacuum tube technology.
U.S. Department of Energy, OSHA, Alliant Energy
Data compiled from The
British Antarctic Study, NASA, Environment Canada, UNEP, EPA and
other sources as stated and credited Researched by Charles
Welch-Updated daily This Website is a project of the The Ozooe Hole