Fundamentals of Electricity

As we build the energy authority website, we remain mindful that many of our readers might benefit from a tutorial of the terms and concepts around each form of energy. So, interspersed among our articles will be writings addressing some of the more basic elements of the principles involved. This article deals with those that underlie electricity.

Electrons – The Beginning

It wasn’t until just before the turn of the twentieth century that the existence of the electron was discovered. Electrons orbit the nucleus of an atom, each with a negative charge, providing the foundational bases for electricity:

• If tightly bounded to the atom as with wood, glass, plastics and even air, electrons will not conduct electricity very well; therefore the term electrical insulator.
• If, on the other hand, the electrons can detach from their atoms fairly easily as with metals, electricity will flow  easily; therefore the term electrical conductor.

Flow of Electricity

So, an electrical conductor is essential to the flow of electricity. But, so is a generator, that forces the flow from point to point through the conductor, and the electrical circuit which directs the flow.

• Generator: Magnets are the catalysts for the flow of electrons, thus the definition of a generator – a device that moves a magnet in close proximity to a wire to initiate the steady movement of electrons. The actual action that initiates this movement can vary, ranging from hand cranks to nuclear fission, but the principle is the same.

The actual number of electrons placed in motion is called current which is measured in amps, and the actual force pushing the electrons is called voltage. This motion requires a circuit to get the electricity to its desired destination.

• Electric Circuit: In its simplest form, an electric circuit is a 2-wired conductor which facilitates the flow of electrons from the negative terminal of the generator to the positive terminal of its load and back. These moving electrons possess energy to create heat, magnetic fields, etc. that in turn, create light, run appliances, and operate electronics.

Electricity Terms and Concepts

The following discussion highlights some of the more commonly used terms and concepts used to describe events and characteristics of electric power systems.

• Voltage, Current and Resistance: Current, an indication of the number of electrons in motion measured in amps, and voltage, the pressure applied in pushing these electrons, multiplied together, define the amount of electricity consumed, termed watts. Recognizing that the power outlets in the walls of U.S. homes deliver 120 volts, and knowing the power capacity of a given electrical device, one can determine the number of amps required to energize and / or operate the device. Your electric bill is based on a kilowatt-hour. So, if a specific appliance uses 1,200 watts (1.2 kilowatts), and it runs for 2 hours, and the cost of a kilowatt-hour is 10 cents, then the cost to run that specific appliance would be 24 cents,  or 12 cents every hour it is operated. Resistance, measured in ohms, is the characteristic that determines the amount of current required to operate a device at its designed wattage. As an example, the filament of a 120-watt light bulb with 120 ohms of resistance will draw 1 amp, where as the filament of a 60-watt light bulb drawing 1 amp will require a resistance of 240 ohms.
• Direct vs. Alternating Current: The power that originates from a power plant is alternating current as the direction reverses (alternates) at region-specific frequencies (e.g. 60 times per second in the U.S.), as is the power that is available at a home wall socket. Direct current, typically produced by batteries, fuel cells and solar cells, flows in the same direction. The major advantage of alternating current is the ease with which power voltage can be changed, using a transformer to significantly increase voltages, allowing for the transport of power over long distances; and then lowering it to the lower voltages for safer home applications.
• Electrical Grounding: Power companies use the earth to ground the power system, making for an effective return path for the electrons Every utility pole has a bare wire that connects the aerial ground wire to the ground, and near each home’s meter are 6-foot long copper rods driven into the ground, to which all the neutral plugs and outlets in a home are connected.

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