Electricity

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 amber.

 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 "ion."

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" (-).

Scientists and 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.

Electricity is 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 conductors.

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.

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 that wire."

Electricity is a basic part of nature and it is one of our most widely used forms of energy. 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. 

http://www.ushistory.org/franklin/info/kite.htm

Beginning with Benjamin Franklin's experiment with a kite one stormy night in Philadelphia, the principles of electricity gradually became understood. 

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.

Nikola Tesla - The Forgotten Wizard

 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. 

• Watts 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.

• Kilowatts 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.

• Megawatts 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.

• Gigawatts 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.

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. 

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 electricity.

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.

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 power lines go into substations near businesses, factories and homes. Here transformers change the very high voltage electricity back into lower voltage electricity.

From these 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 your neighborhood.

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 appliances.

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.

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. 

• U.S. Power Grid