G. Casey Cassidy
What is electricity? Can you see it or touch it and if you can’t, then how do you know it exists? The answer lies with the effect that electricity produces. You can’t see electricity but you can see the work that it accomplishes. Electricity can be described as a flow of electrons that travel at a rate of 186,000 miles per second. It produces heat and light and power for household appliances and industrial machinery. Because electricity is so versatile, it has become a major source of energy today. Electricity itself is not a source of power. Electrical power stations burn coal or other fuels to produce steam and it’s this steam that produces the energy to power generators that produce electricity. Hydroelectric power stations use waterfalls as energy sources with nuclear power stations producing energy as well.
In traditional steam power plants, energy is produced when oil or coal is burned to heat water which converts to steam which in turn powers huge turbines. These turbines produce energy which enables generators to produce electricity as a result of their interaction with magnetic fields within the generators themselves.
Nuclear power plants operate in a similar capacity except that uranium is used in lieu of coal or oil. In this process of nuclear fission, the splitting of the atoms into lighter elements releases heat and the free neutrons, interacting with other uranium nuclei, allows the process to continue, the released heat causes the water to boil, producing steam, which ultimately produces electricity.
But enough about the production of electricity. Let us move to electrical usage in our homes and schools with particular emphasis on electricity recorded by electrical meters. In order to understand the functions of electrical meters, we need to understand specific units which are used to measure electricity and their relationships to each other. A Volt is the unit which measures the potential difference between two points on a circuit. The current, in most household and school receptacle outlets, runs at a constant pressure of 120 volts. As the current moves from the supply wire through the appliance or light, it loses voltage. When the current leaves the load unit and enters the return circuit, it has expended all its voltage. An ampere is the unit used to measure current, that is the number of electrically charged particles called electrons, which flow past a given circuit point each second. Current which has lost its voltage still has an amperage as it completes its circuit and returns to the power plant.
Watt is the unit of power. It indicates the rate at which a device converts electrical current to another form of energy, subsequently consuming that energy. Kilowatt-hour is the unit of energy measuring the total amount of electricity that is consumed. The relationship of volts, amperes and watts to one another is expressed in a simple equation that enables us to make any calculations needed: Volts X Amperes = Watts. If your current is 120V and an appliance requires 5 Amps of current, then the equation would read: 120V X 5 Amps = 600 Watts. Similarly, to estimate the current needed for an appliance rated in watts, one would simply turn the equation around: Watts Volts = Amperes. For example, if you had an appliance such as a microwave that used 2400 watts, the equation would read: 2400 Watts / 120 V = 20 Amps.
Having introduced our students to the basic concepts of electricity and the functions of specific units which are used to measure electric usage, practical learning experiences using simulated meters provided by the local utility company will enhance their learning experiences. Hands on activities, as previously noted, will facilitate their learning processes. Our local electrical utility willingly provides guest speakers to introduce this material. Additionally, pamphlets such as “You and Your Electric Company” and “How to Understand Your Electric Bill” and “How to Read Your Meter” will be provided and discussed to help students record daily meter readings at home and to calculate monthly electrical consumption. Students might consider drawing their own electrical meters complete with individual measurement expenditure dials to reinforce their understanding of the pamphlet information. They might also consider inventory assessment lists of primary electrical appliances in their own homes, identifying high, medium, and low energy consumption devices by multiplying the kilowatt hour cost by the number of kilowatt hours that the appliance uses. In this way, students will begin to realize how energy is consumed daily, monthly and yearly and subsequently, they can begin to become more responsible for their use or abuse of electrical energy. Together with their parents and other family members, they can embark on a conservation program that hopefully will extend to other utilities which are used in the home and perhaps, this learning process will extend to cooperative monitoring of energy uses at Clemente Middle School as well.
The pamphlet “How to Understand Your Utility Bill” should be assigned as homework for parents and students alike. The material covered includes terms such as the B.T.U., cubic feet, watt, kilowatt, fuel adjustment cost, and rate schedules. Major topics are “How to Read Your Electric and Gas Meters”, “How to Apply Your Meter-Reading Skills,” “How To Understand Your Electric and Gas Bills” and “Energy Costs of Major Home Appliances.” The pamphlet itself is easy reading and subsequently, self-explanatory.
Every year, the world wide demand for electricity increases. In the Unites States we use approximately four hundred times as much electricity as we did in 1900 and roughly twelve times as much since World War II. And as we approach the 21st Century, our demands for electricity are ever increasing. Therefore, it behooves all of us to do our part in helping to conserve our natural resources. There’s an old expression that goes “charity begins at home” and I’d like to paraphrase that statement just a bit to suggest that conservation of energy begins at home as well, and hopefully our students can make a real difference for their lives and the lives of their children.