Lesson 6.5: Insulators/ConductorsEssential Concepts: Electricity requires a circuit to flow A complete circuit can be constructed in more than one way using the same materials Different types of electric circuits show different behaviors (parallel and simple circuits) Electricity can drive the production of light heat and sound Insulators and conductors of electricity Background: · Remember electrons? Electricity is the flow of electrons · In order for electrons to flow, they need a source (like a battery), a path (a conductor), and this path must form a complete circuit (like a loop) · In order to prevent a short circuit, the circuit must also contain something to use the electricity – like a light bulb or a resistor or a buzzer. These are termed loads. · This is how electricity drives the production of heat, light, sound, etc. · A simple loop with all loads connected in line (in series) is called a Series Circuit. · Two loops, both connected to the battery, each with it’s own loads is called a Parallel Circuit. · A series circuit is a Voltage Divider. Two light bulbs on the same series circuit share the voltage of the battery: if the battery is 9V, then each bulb gets 4.5 volts. · A parallel circuit avoids this problem. Two bulbs in a simple parallel circuit each enjoy the full voltage of the battery. This is why the bulbs in the parallel circuit will be brighter than those in the series circuit. · Another advantage to the parallel circuit is that if one loop is disconnected, then the other remains powered. Example: good holiday lights can have a bulb removed and the rest of the lights on the string will remain on. · Materials through which electrons can easily flow are called conductors because they conduct electricity well · Materials which retard the flow of electrons are called insulators because they keep electricity from moving · Most metals are good conductors ex: copper, gold, silver · Insulators are very common: most plastics, wood, glass, leather, etc. Goal: Students will experiment with batteries, bulbs, and wire so as to understand the idea of a simple circuit Objectives: Students will become familiar with the use of wirestrippers, fahnstock clips, battery holders and bulb holders Students will follow a series of questions that will allow them to create and identify series and parallel circuits Materials: Cardboard boxes to hold individual materials D size batteries Wire #48 bulbs Battery holders Bulb holders Wire strippers Sheet: Check list, Assignment sheet Procedure: Before class set up: Materials can be put into boxes so that the students begin with the very basic components and then add materials as they are required. To start the lesson, each box should have: one piece of wire, one bulb, one D battery. It is useful to have some way to keep the bulb from being smashed by the battery—I used a cardboard divider and tape to make a small bulb compartment. Materials that will need to be sorted and ready: Pieces of wire, 3-4 inches each D batteries Bulb holders Battery holders Wire strippers Paper clips Brad fasteners index cards
The following Final Projects are possibilities:
4. The students should not begin their Final Project until they have completed the checklist of experiments. By doing the checklist, they are learning the necessary skills to complete the project. It is a good idea for the teacher to have an assignment sheet for the Final Project and an Experiment Checklist sheet, so as to reference both while explaining the forthcoming lessons(ie..”When you are done with this, you will get this.”) If you are assigning the Explorer Final Project, then give them their explorer names so that they can start researching for homework. Check with the Learning Center teachers to determine which explorers might be easier to research. 5. Explain that they will be able to work independently, but there will be times when they will all have to direct their attention to the whiteboard or to the teacher for hints. For example, If they decide to put one wire to each end of the battery, it will get hot. They can try this for a few seconds, but they should know that 1. this can hurt after a while and 2. this will waste the battery and they will have to bring in a new one. Hopefully, we will find out why this occurs as we learn about electricity. (The electrons have no load to cross, the result is heat energy) 6. First Lesson: Give out a wirestripper and an experiment box. Explain that the wire is similar to an arm with a shirtsleeve covering it. Have them notice the little notches on the wire stripper. These are what keep it from being a pair of scissors(also the fact that they are not sharp). You can put the wire in these notches. Now, if we were putting a giant wire stripper over my arm, the goal would be not to cut the arm but to rip off the shirt sleeve thus leaving the arm bare. So we have to put enough pressure on the stripper to grab the shirt, but not the arm underneath. It is the same with the wire and with some practice, everyone will soon be stripping wires. The students can try several times, but don’t worry if you don’t get it right away—you will have time later to practice. You only need to strip several centimeters of wire at each end. Have prestripped wires available for kids who don’t get this right away so as to save time. 7. The kids can now have the boxes—it is also time to give them the checklist and to go over it. Explain how you want their diagrams to look. If they know they have to have 8 diagrams, how can they set up their page ahead of time? What is too big, too small? How do you label? What about name and date? Practice drawing a bulb(circle, two squiggly lines, triangle—so easy) and battery (label + and - )for them on the board without showing any wiring connections. Teacher Worksheet info—the reason not to give them the bulb/battery holders right away is so that they will appreciate these wonderful devices, also so they will really get a sense of where you have to put the wires to make contact. As an extra credit challenge, you can have students design their own bulb holder.(tin foil, folded index card with hole, tape-- works)Remind them that positive and negative are not the same. First experiment has 4 possible ways to light up and 4 “does not light” diagrams Second Experiment has 4 possible and 1 “does not light” diagram Fourth Experiment could be 2 right or 1 right one wrong Both bulbs dim is series, both bright is parallel Hopefully, by the time they get to the bottom of the sheet, they will already have done a series and parallel circuit—yes, they have to do it again (but, no diagrams...).
If you look at a light bulb, you can see that there is something(glass or plastic) holding the wires apart and that one wire goes to the “side” and the other goes down to the “tippy-tip.” The filament is a thin wire—do you think there is air in the bulb? (no, gas or nothing) why not? Does a bulb get hot at your home? (Be careful--hot) Are there different kinds of bulbs? (yes) Why don’t some need wires? (gas and coating inside) What about the battery? Are there different kinds of batteries? Remember our “18” rule! What is inside of a battery? We have to be careful of that stuff—if you see a leaky battery, alert the teacher and wash your hands. The path of the electrons is like a car that travels a road and needs to get back to where it started in order for the light to go on. Switches are like draw bridges in the road. This is a useful way to talk about a switch and the need to complete the journey—but the misconception is that it is only one “piece” of electricity moving around—remember it is a bunch of electrons bumping each other along a path. When all students are halfway through the checklist, give them an assessment “quiz” on whether or not the bulb will light up with various connections (Lesson 3 Activity sheet 1)and what to do if it doesn’t and what to do if you see a downed wire(Post Assessment sheet #2). These are all from the NSRC/STC Electric Circuits Teacher’s Guide ISBN 0-89278-661-2 that is a must have for this unit. Remember to check students for neatness or errors in their diagrams.
· Children can poke holes with a pushpin and then make the holes wider with a pen. · LED (Light Emitting Diodes) are very attractive—however electricity can only run through them in one direction and they require a specific amount of electricity—they may require a resistor. · Be very careful about children wishing to solder—they must have adult supervision. · Holiday lights are a quick and easy modification for children experiencing difficulty with this unit. Make sure that you cut the plug off of the string of lights and throw it away!!! Once children have cut sections of the wire apart, you do not want anyone plugging it in! Activities: discussion, diagram drawing, experimenting with circuits, testing conductors/insulators, designing and creating Final Project Electric Circuits Name____________________ Class _______ These are the experiments you need to complete in school before you can start on your final project. Have a classmate put his/her initials on the line after they have seen you successfully complete the experiment and than color in the O. Draw diagrams to communicate the ways in which you solve the problem. Note: some diagrams may show methods that do not light the bulb. ___O Light one bulb using: 1 bulb, 1 wire, 1 battery. ___O 8 Diagrams How many different ways can you light the bulb? ___ ___O Light one bulb using: 1 bulb, 2 wires, 1 battery so that the wires do not touch each other. ___O 5 Diagrams How many different ways can you light the bulb? ___ ___O Learn how to use a bulb and battery holder ___O Light two bulbs using: 2 bulbs, 2 bulb holders, wire, 2 batteries, 2 battery holders. ___O 2 Diagrams Can you compare 2 different ways of wiring the bulbs so that in one way the bulbs are brighter than in the other way? _____ ___O Make a switch. Be creative. Solve the problem. ___O 1 Diagram ___O Complete the Insulator/Conductor list. ___O Make a series circuit with a switch. ___O Make a parallel circuit with a switch. ___O Sketch a diagram of your Final Project. Make sure that all of your diagrams have labels, including the + and – sides of the batteries used, and whether or not the bulb lights up or not. ** Note: all of the above should be on one worksheet — set top and bottom margins to .5 inches ** Conductors or Insulators ? Name__________________ Class_________ Have you made a switch for a circuit yet? If yes, you may use that switch or you may wish to use the following idea: Materials: One index card Two brass fasteners One paper clip Two wires Procedure: 1. Poke the fasteners through the index card so that they are close enough to each other so that a paper clip can touch both of the fasteners. Now attach wires to the fasteners.
2. Now attach the paper clip to one brass fastener so that it can swing around and touch both brass fasteners. The paper clip should also be able to swing to a position where it is only touching one of the fasteners.
__________________________________________________________________ Now take off the paper clip. Now you have a Conductor Tester. Place items so that they touch both brass fasteners. Does the bulb light up? Make a list of 10 items that light up the bulb. (They are Conductors -- they conduct electricity) _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ Make a list of 10 items that do not light up the bulb. (They are Insulators -- they do not conduct electricity) _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ _________________________________ ** Note: all of the above should be on one worksheet — set left, right, top and bottom margins to .5 inches ** Circuits Name __________________ Class ______ Date _______ Draw diagram of a series circuit. Make sure to label the following: Battery Positive (+) Negative ( - ) Bulb Switch Draw a diagram of a parallel circuit. Make sure to label the following: Battery Positive (+) Negative ( - ) Bulb Switch *Science Project* Dear Parent or Guardian, Your child will be working in class to create an electricity project that will focus attention upon explorers of the 15th and 16th centuries. Each child will be assigned a person to research. They must use their information to create an interactive exhibit that will inform the user about their individual explorer. The students will be asked to use skills they will develop in science class to complete this project. They may create maps and draw illustrations, diagrams, or charts. They may ask questions as long as they present answers. They must have a working series circuit or a working parallel circuit with a switch in their project. They must organize their information so that it is easy for the observer to understand the historical significance of their explorer. They must write neatly and use size and color to their advantage. Some of the information they might include about the explorer: Government & Country that financed the expedition, motivation for exploration, relationship to encountered native populations, route taken, significant dates, repercussions of the voyage, a map showing pertinent locations, or Interesting Information. Your children will be working on these projects during science class every day. You may wish to purchase some extra materials for them to work with. Purchasing materials is not necessary for your children to successfully complete this project. Purchasing additional materials will allow them greater freedom to experiment on their projects. Batteries usually last through the duration of the project. Some students prefer 9volt batteries, as they are easier to mount onto their poster. The light bulbs tend to need to be replaced two or three times. Holiday lights are an inexpensive and acceptable solution. LEDs are fun and make the project more attractive—they also present extra challenge and may need resistors. You can purchase 20 LEDs for about $2. 50. Battery holders are helpful. Bulbs should be able to run on 1.5 or 9 volts. The electrical wiring of these projects is to be done in school and should not be worked on at home. The project is due . Please sign below to indicate that you aware of this project, the due date, and the student’s responsibilities. Thank You. Student Name __________________________________ Parent signature __________________________________ ** Note: all of the above should be on one worksheet — set left, right, top and bottom margins to .5 inches ** The Explorer Science Project Name ____________ Class ________ Using your textbook, library books, or other sources, create an exhibit that presents information on: ______________________________________________________ You must include the following information: Country Represented : _____________________________________ Year of Exploration: _____________ Land Visited: _________________________________________________ Route of Voyage
Some of the information you might include about the explorer: motivation for exploration, relationship to encountered native populations, significant dates, repercussions of the voyage, a map showing pertinent locations, a timeline, biographical data, or information of interest. Due Date: _________________ ** Note: all of the above should be on one worksheet — set left, right, top and bottom margins to .5 inches **
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The diagram shows two circuits in these circuits only the internal resistances differ
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