Electricity Basics
What is Electricity?
Alternating Current vs. Direct Current
Electricity and Magnetism
U.S. Sources of Electricity
U.S. electricity usage
Electricity Terms
Different sources of electricity






What is Electricity?

Electricity has no clear definition since it is so often misused to describe a variety of phenomenon. People commonly use the term electricity to describe electric charge , electric current , and electrical energy . Different definitions of electricity can be found in different places, underscoring our incomplete picture of the complexity of this natural phenomenon.

Electric charge is a fundamental property of some subatomic particles. Electrons have a electric charge of -1 and a proton has the charge of +1, as do other subatomic particles and ions.

Electric current describes a flow of electric charge. Electric current is either Direct Current (DC) a single-direction flow, or Alternating Current (AC) which describes a current that repeatedly changes direction.

Electrical energy is a form of energy present in an electric field or magnetic field, electrical energy is measured in joules.

Electric power is the name given to electrical energy production and distribution.

Most people think of electricity as the flow of electrons through a wire. Since electrons are a fundamental part of the physical world, to make electricity we need only find a way to make them flow! To find out how this is done, check out generating electricity .

What is Electricity Really?

OK, let's not try to dodge the question. It turns out that there are two main things which travel through the wire, electric current and electric energy. So what is the difference?

Consider this, exactly the same amount of electric current flows out of a light circuit that flowed into it. Since energy is clearly released as heat and light, we would expect a reduction in current. But this is not the case, so we call the energy released as heat and light Electric Energy - also known as electromagnetic energy.

If you are interested in an in-depth and more metaphysical look electricity at electricity, you should find this article quite interesting. The three most basic units in electricity are voltage (V), current (I) and resistance (r). Voltage is measured in volts, current is measured in amps, and resistance is measured in ohms. The current refers to the number of electrons moving through the wire. The voltage refers to the pressure at which these electrons are being forced to move. The resistance refers to the capacity of the conductor. A basic equation exists I = V/r which says current is equal to voltage divided by resistance.






Alternating Current vs. Direct Current

Batteries, fuel cells, and solar cells all create direct current (DC), which means current always flows in the same direction, originating in the negative terminal and flowing towards the positive terminal. Power plants, on the other hand, deliver alternating current (AC). Alternating current means just that, the direction of the current reverses, or alternates 60 times per second.

The standard power outlet in the U.S is 120-volts 60-cycle AC power.

A primary benefit of AC power is that it can travel long distances without energy loss. Power lines carry very high voltage current and a transformer is used to convert the current to 120 volts just before it is delivered to your home.








Electricity and Magnetism

There is a very strong link between electricity and magnetism. If you move a magnet near a wire the magnetic field will cause electricity to move in the wire. In turn, when electrons move through a wire it creates a magnetic field around the wire. To better understand this, visit generating electricity .














Sources of Electricity:

The electricity that powers your appliances and other devices comes from many different types of power plants, mostly from coal plants, natural gas plants, and nuclear facilities. The primary renewable electricity power comes from wind and geothermal sources. All these power plants contribute power to a large national grid, a collective energy pool. Whenever you use electricity, the energy comes from this pool.

2004 Sources of Electricity:

52 % Coal
21 % Nuclear
14 % Natural Gas
9 % Renewable Energy
3 % Petroleum

Source: EIA (eia.doe.gov)









U.S. Electricity Usage

U.S. consumption, estimated in 2002 was 3.66 trillion kWh (CIA fact book). The average U.S. household consumes about 10,000 kWh of electricity each year.













Electricity Terms

Watt, wattage, watts Generated electricity is measured in watts. Wattage is determined by multiplying the voltage by the amperage. Watts = Volts * Amps
Since a watt is a very small unit of electricity (e.g. a lightbulb might be 75 Watts ), the terms kilowatt kW (1,000 watts), megawatt MW (1 million watts), and gigawatt GW (1 billion watts) are commonly used.

Amp, amperage, amps A The number of electrons moving in a wire is called the amperage, an amp is a unit of electric current.

Volt, voltage, volts V Electricity flowing, whether from batteries or generators, has a force or a pressure forcing the electrons out the negative terminal. This force is called the voltage and is measured in volts.

hertz Hz A unit of frequency equal to one cycle per second

kilowatt-hours (kWh): Electricity consumption and production is often measured in kilowatt-hours (kWh). A kilowatt-hour describes one kilowatt (1,000 watts) of electricity produced or consumed over one hour. For example, a 100-watt light bulb running for 10 hours requires one kilowatt-hour of electricity (100 watts x 10 hours = 1 kilowatt-hour = 1,000 watt-hours).

A generator is an engine that converts mechanical energy into electrical energy by electromagnetic induction.

Electromagnetic Induction - Electromagnetic waves propagated by induction through an electromagnetic field.

Alternator : An alternator is a generator that produces alternating current.

Armature : a component of a generator, the coil of copper wire which spins between the magnets.

Transformer : attatched to your power pole, the transformer converts high Voltage electric current into the 120 Volt current your home uses.