Follow electricity from a power plant to a home. Here is how the trip goes, one step at a time. It is made at power plants, and power lines carry it over long distances. At a substation, a transformer lowers the voltage. From a substation, smaller, lower-voltage lines bring electricity to neighborhoods and homes. People use electricity to light their homes. The electricity we use is a secondary energy source. It is made by converting primary sources like coal, natural gas, nuclear, solar and wind energy. That is the trip. Now let us look at what is really moving.
What is it that makes that long trip? Let us look closer. The word “electricity” comes from “elektron,” the Greek word for amber. Today we explain it with the atom. Atoms are made of protons, neutrons and electrons. Outer electrons in an atom have a weaker pull toward the protons. They can move from one atom to another. These shifting electrons are what we call electricity. Metals let electricity flow through them easily. Glass, rubber, wood and plastic do not. Electricity only flows when it has a complete path, called a circuit.
Electricity involves electrons moving from place to place. Electrons show up in more places than wires. Static electricity can make your hair stand on end. Rubbing can move electrons from one thing to another. That is how static electricity starts. Electric charges that are alike push each other apart. Let us see how it builds up. Lightning is a kind of electricity too. It happens when electric charge builds up in a storm cloud. Then it jumps to the ground. Benjamin Franklin showed that lightning is electricity.
In 1831, Michael Faraday made a discovery that power generation depends on. Moving a magnet through a coil of wire can make electricity flow in the wire. A generator turns the energy of motion into electricity. In a turbine generator, a moving fluid pushes blades on a rotor shaft. The fluid can be water, steam, combustion gases or air. The spinning shaft turns a generator. Wind can spin the blades of a wind turbine, and moving water can spin a turbine too. Wind is caused in part by the sun heating the air unevenly. Solar panels can use sunlight to make electricity.
Light is where many people see electricity at work. Before electricity became widely available, candles, whale oil lamps and kerosene lamps provided light. Iceboxes kept food cold, and wood or coal stoves provided heat. Thomas Edison invented a long-lasting light bulb around 1879. On 1 November 1879, he patented his lamp. His laboratory had got a glowing thread that lasted more than fourteen hours. Light bulbs also show how electricity is counted. A kilowatt is 1,000 watts. A 40-watt light bulb used for five hours uses 200 watt-hours, or 0.2 kilowatt-hours, of electrical energy.
Words to know
- electrons: tiny moving charges
- circuit: complete path
- turbine: spinning blade machine
- transformer: voltage changer
- generator: makes electricity
