Thursday, April 12, 2012

All About Electricity

Electric power holds an interesting place in our lives. We use it every day to communicate with loved ones, cook our food, and even keep ourselves alive with machines. In spite of this importance, we don't often think about the forces at work when we heat our cup of soup in the microwave. For many of us, it's been quite a long time since we learned about this stuff in school. Let's look back on how electricity works and find out a little bit about how much juice we really use.

What is Electricity?
Electricity starts with the atom, a basic building block of matter. Atoms are made up of three particles: protons, neutrons and electrons. Those first two particles are much larger than electrons and cling to each other in the center of the atom, the nucleus. Electrons orbit the nucleus in shells. The electrons in the furthest shell are called valence electrons, and are the ones most easily moved.

Remember the saying, "opposites attract?" Well, protons have a positive electric charge and electrons have a negative charge. (Neutrons have no charge at all.) Those valence electrons are not pulled as strongly to the protons, so they can be pulled away by electromagnetic forces. When that happens, electrons flow, and that is electricity.

Electricity likes to flow until something stops it, and some materials are better conductors than others. Those electrons love to course through most metals and water. That's why wires are made of copper and swimming during a thunderstorm is a bad idea. Wood and plastic, on the other hand, are poor conductors.

Electricity History
Humans have experienced electricity, even if we didn't really know what it was. Remember the last time you walked across a carpeted room and then got shocked by a doorknob? As you your feet moved across the carpet, negatively charged electrons built up on your person. When you touched that metal knob, the electrons followed the path of least resistance and zapped your hand as they flowed through.

Although archaeologists have also found primitive batteries made by people in Ancient Mesopotamia, electricity has only been harnessed for practical use in the last couple of centuries. In the late 1700s, Benjamin Franklin did his famous key-on-a-kite experiment. He didn't understand the force completely, but he knew that lightning was likely to follow metal. One of his many inventions was the lightning rod. Once a long, tall conductor was grounded near a building, a lightning strike was much more likely to flow into the earth instead of the building. Franklin was one of America's early firefighters, so his early understanding of electricity prevented a lot of property damage and saved lives.

The "killer app," the one big application that made electricity indispensible, was the invention of the electric light bulb. Where the rising and setting of the sun once set a person's schedule, artificial illumination allowed people to work into the night, made city streets safer and more. Thomas Alva Edison patented the first reliable light bulb in 1880, and soon after, the American electric grid started to form.

As electric power became ubiquitous in the United States, more and more appliances began to make use of the resource. Parents once made their children toast by placing bread in a cumbersome metal pincer they put into a stove. The electric toaster is just one invention that makes the American lifestyle so easy and productive. (It also allows us to enjoy delicious frosted strawberry toaster pastries!)

Electricity Use Today
Opening up your utility bills probably isn't the most fun you have all month. It is, however, interesting to note how much electricity we use and how much it costs.

Electricity is measured in units called "kilowatt hours." This represents the electric power transferred to you multiplied by time (in hours, obviously). In 2007, United States residential consumers just like you consumed almost 124 million kilowatt hours (kWh) of electricity. California has the honor of being the state with the highest level of residential electricity use, at almost 13 million kWh. (The state of Texas comes in at number two, with 9.2 million kWh.)

The average cost for electricity varies, depending on state and region. This makes a lot of sense; it costs a lot to generate electricity in Hawaii, as you have to transport the fossil fuel used to run the power plant to the middle of the Pacific Ocean. Homeowners in sparsely populated areas may also pay more because of how much it costs to build and maintain power lines to relatively remote places. The average Texas electric customer pays $140 for service each month.

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