| “Tell me and I forget. Teach me and I remember. | | | | electricity to flow. Think of a circuit as a circle. When |
| Involve me and I learn.” (Benjamin Franklin) | | | | the circuit is complete, electricity can flow; we call that |
| These wise words are as true today as they were | | | | a “closed” circuit. When there is a break |
| more than two hundred years ago when Benjamin | | | | anywhere in the circuit, electricity cannot flow, and we |
| Franklin first made this statement. That Franklin was | | | | call that an “open” circuit. Second, |
| one of the foremost minds of his time is well known. | | | | electricity is lazy. It will always follow the path of least |
| Yet, clearly, he also understood the value of using his | | | | resistance. |
| hands as well as his head when it came to learning. | | | | Electric circuits are comprised of three connected |
| Franklin knew that science isn’t just a collection | | | | parts: |
| of facts. You can no sooner understand science by | | | | 1. An energy source, such as a battery |
| memorizing facts than you can understand music by | | | | 2. A conductive path for the electricity to flow through, |
| memorizing a score. You have to do science just like | | | | such as a wire |
| you have to play music to really “get it.” | | | | 3. A load that uses electricity to do work, such as a |
| What better way is there to shape our minds, expand | | | | light bulb |
| our knowledge, and enhance our understanding of | | | | Try This at Home! |
| physical science than hands-on experimentation fueled | | | | Here’s a simple circuits experiment you can do |
| by curiosity? | | | | with your children. All you need is a battery (AA, C, or |
| Franklin’s insatiable curiosity, love of science, and | | | | D will work), a small piece of wire, and a flashlight bulb. |
| hands-on approach led to numerous discoveries and | | | | If you don’t have them at home, you can get |
| inventions, especially in the area of electricity. The story | | | | the wire and bulb from any hardware store, electronics |
| of his kite-flying experiment during a thunderstorm has | | | | store, or the science fair section of a hobby shop. We |
| become part of American lore, and the lightning rods | | | | used some surplus electric fence wire we had at |
| that he invented are still saving property and lives to | | | | home and borrowed a bulb and battery from a |
| this day. However, despite the many advances in, and | | | | flashlight. |
| widespread use of, electricity since Franklin’s | | | | Connect the bulb to one side of the battery as shown |
| time, it is understood surprisingly little. | | | | in Figure 1. We’ve connected the bulb to an |
| What Is Electricity? | | | | energy source, so why doesn’t it light up? It |
| Electricity is such an integral part of our daily lives that | | | | doesn’t light up because it’s an open |
| it would be difficult to imagine society today without it. | | | | circuit: there’s no path on which the current can |
| Yet, we normally cannot see, taste, smell, or touch it. | | | | get back to the other side of the battery to complete |
| So, what is it? | | | | the circuit. Now connect the circuit as shown in Figure |
| Generally speaking, electricity can be described as | | | | 2. The current flows through the bulb back to the |
| “the flow of electrons in a conductor.” | | | | battery and the bulb lights up. Congratulations, |
| Electrons are negatively charged subatomic particles | | | | you’ve just created a working circuit! |
| (extremely small parts of an atom). They travel in | | | | Now let’s modify that circuit to build an insulator |
| orbits around the protons and neutrons of an | | | | conductor tester. You’ll need two more wires. |
| atom’s nucleus, much like the planets in our solar | | | | You may find it easier to use jumper wires with |
| system travel in orbits around the sun. | | | | alligator clips. (These are small versions of the jumper |
| Conductors are materials (usually metals) that permit | | | | cables for your car and can be found in the same |
| electrons to flow through them. Most metals | | | | shops mentioned above.) |
| don’t hang on to their outermost electrons very | | | | Connect one end of the battery to the bulb. Connect |
| strongly. So when an electrical charge is applied | | | | one jumper wire to the other side of the battery and |
| across a conductor, it causes those loosely held | | | | the other jumper wire to the other side of the bulb. |
| electrons to move from one atom to another to | | | | (See Figure 3.) Now when you touch the loose ends |
| another, thus creating a flow that we commonly refer | | | | of the jumper wires together, the circuit is complete |
| to as “electricity” or “electric | | | | and the bulb lights up. So if we put a conductor |
| current.” | | | | between the free ends of the jumper wires, the bulb |
| Experience tells us that electricity doesn’t flow | | | | will light. If we put an insulator there, the bulb will not |
| through everything. If it did, we’d get a shock | | | | light. |
| every time we turned on a lamp or plugged in a | | | | Metals will usually conduct; experiment with coins, keys, |
| vacuum cleaner. Once again the Creator has revealed | | | | pencil lead, foil gum wrappers, etc. Non-metals will |
| His genius. He has provided us with both conductors to | | | | usually insulate; experiment with plastic cups, glass, |
| carry electricity and insulators to safely separate us | | | | painted objects, wood, etc. Have your children record |
| from it. Insulators, then, are the opposite of conductors. | | | | their predictions before they test an object, and then |
| They hold on to their electrons so well that current | | | | record the results after the tests. This can lead to a |
| does not flow through them. | | | | discussion of the properties of conductors and |
| If you’ve ever been shocked after walking | | | | insulators. They may be interested to know that |
| across a carpet in socks and then touching a | | | | materials that are good conductors and insulators of |
| doorknob, you’ve experienced static electricity. | | | | electricity are also good conductors and insulators of |
| As a result of your feet rubbing across the carpet, a | | | | heat. |
| negative charge built up on your body. That charge | | | | Conclusion |
| had nowhere to go (hence the term static) until it | | | | Through these simple experiments, you’ve |
| encountered the metal doorknob and discharged all at | | | | begun understanding the fundamentals of the |
| once. | | | | technologies that play an increasing role in our modern |
| You can perform a simple static electricity experiment | | | | lives. So don’t let the fun stop now. Add electric |
| at home with a balloon and a piece of paper. Begin by | | | | circuits to your curriculum. There are a number of |
| rubbing the blown-up balloon vigorously against the hair | | | | hands-on teaching materials available today (although |
| on your head or against a wool sweater; then hold the | | | | attractively packaged, don’t settle for toys), and |
| spot that was rubbed up to a wall and let go. The | | | | parents need not be engineers to help their children |
| balloon will stick. The rubbing pulled electrons from your | | | | fully, safely, and correctly learn about electric circuits. |
| hair to the balloon. Since electrons don’t flow in | | | | The son of a son of an engineer, David M. Jones has |
| an insulator (such as the latex balloon), they stay put, | | | | long been fascinated by science and technology. With |
| and the negatively charged portion of the balloon is | | | | two engineering degrees and more than twenty-six |
| attracted to the wall. | | | | years of experience, he recently co-founded Edamar, |
| Now tear up the paper into small pieces and rub the | | | | Inc. and has turned his energies toward helping others |
| balloon again. You can pick up the small bits of paper | | | | learn the fundamentals of science in an increasingly |
| with the charged portion of the balloon. A strong | | | | technology-driven world. Learn about Edamar’s |
| enough charge will actually cause the pieces of paper | | | | exciting new approach to hands-on science at |
| to leap up to the balloon. | | | | ©2008 The Old Schoolhouse® Magazine, LLC |
| What About Circuits? | | | | This article originally appeared in the Fall 2008 issue of |
| Electricity doesn’t do us much good unless we | | | | The Old |
| can control it in order to do useful work. Scientists | | | | Schoolhouse® Magazine, LLC |
| learned to do this with circuits. First, they discovered | | | | Reprinted with permission from the publisher. |
| that a circuit must be complete in order for the | | | | |