KHOWLEDGE ZONE

Watch a bolt of lightning flash across the sky. Flip a switch and light up your bedroom. Click the remote and see the TV come on. What do all of these things have in common? Electricity.

WHAT IS ELECTRICITY?

Electricity is a powerful force of nature. Electricity is everywhere in the universe. Electrical forces hold water, metals, and all other kinds of matter together. You can walk and run because electric signals go through your nerves from your brain to your muscles. The signals tell your muscles where to move.

Electricity makes many machines work. Electricity makes bulbs light up and runs motors in saws, fans, hairdryers, and other appliances. The computer you are using works because of electricity.

WHERE DOES ELECTRICITY COME FROM?

Electricity starts with atoms. Atoms are tiny bits of matter much too small for you to see. Everything in the universe is made up of atoms.

Atoms have two main parts: a center or nucleus, and electrons that orbit or go around the nucleus. Electricity comes from electrons. You cannot see electrons and you cannot see electricity. You can see what electricity does because of electric charge and electric energy.

WHAT IS ELECTRIC CHARGE?

Electric charge comes from the parts inside atoms. There are two kinds of electric charge called positive charge and negative charge. Positive charge comes from the nucleus of an atom. Negative charge comes from electrons. Atoms do not normally have any overall charge because their positive and negative charges cancel each other out. Charge comes when electrons move away from an atom.

Positive charge is just the opposite of negative charge. Positive and negative charges pull toward each other. The pull of positive and negative charges makes two kinds of electricity—static electricity and electric current.

WHAT IS STATIC ELECTRICITY?

Did you ever get a shock after walking across a carpet and touching a metal doorknob? That shock came from static electricity. Huge amounts of static electricity cause lightning.

Electrons that move away from their atoms cause static electricity. You can make static electricity by rubbing certain materials together. Run a plastic comb through your hair. Be sure your hair is clean and dry. Electrons jump from your hair to the comb. This gives the comb a negative electric charge. Your hair loses electrons. This gives your hair a positive electric charge. Hold the comb above your head and watch some of your hairs stand on end. Your hair stands on end because the positive and negative charges are pulling toward one another.

Static electricity also causes lightning. The pull of positive and negative charges between clouds and the ground creates a huge spark. The spark is actually the charges moving very quickly toward each other. Lightning can also be caused by opposite charges inside one cloud, between two clouds, or between clouds and the air.

WHAT MAKES LAMPS LIGHT UP?
Electric current makes lamps and all other electric devices work. Electric current is actually electrons moving in a big loop.

Something must give the electrons a push to get them moving. Batteries can start electrons flowing. Batteries are a source of electric energy. A battery, two wires, and a light bulb can make an electric circuit. The current starts flowing from the battery through a wire to the light bulb. The other wire carries the electric current back to the battery. If you cut the wire, the electric current stops. Switches on an electric circuit turn the current on and off. This is how a wall switch works to turn lights on and off in your home.

The electric energy in your home does not come from batteries. You plug appliances into electric outlets in your walls. The electric energy in the outlets comes from electric power plants.

HOW DO POWER PLANTS WORK?

Huge electric power plants generate or make electricity. Steam or falling water in dams make big machines called turbines turn. The turbine drives another machine called an electric generator. The generator makes electricity.

Long power lines carry electricity from power plants to your home. Wires inside your home bring the electric energy to light bulbs, TVs, microwaves, and your computer.

WHO DISCOVERED ELECTRICITY?

For thousands of years people knew that a material called amber mysteriously pulled on some materials. The ancient Greeks called amber elektron. Scientists in Europe in the 1600s and early 1700s called the materials that amber attracted electrics.

Benjamin Franklin, an American printer, patriot, and inventor, experimented with electricity. He thought lightning and electricity were the same thing. He did a dangerous experiment in the mid-1700s to find out. Franklin flew a kite during a thunderstorm. He attached a metal key to the kite string. An electric charge ran down the wet kite string to the key. The charge made a spark when it hit the key. This showed Franklin that lightning was electricity. He was lucky he was not killed.

Many other scientists have experimented with electricity since Benjamin Franklin. They learned how to make electricity with batteries. They found that electricity would go through wires. An American inventor named Thomas Alva Edison invented many things that use electricity, including the electric light bulb.