Introduction to Exciting Electricity This series is divided into 4 segments, 1 hour each, for a total of four hours. Purpose: In these activities, students will: discover electricity flows in a circuit discover electricity doesn’t work when the circuit is broken identify insulators and conductors discern an electrical current creates a magnetic field perpendicular to the current learn the symbols used to indicate a battery, the resistors, the wires, and the positive and negative sides to the battery learn to draw a simple electrical schematic (diagram) recognize how to connect a simple, series and parallel circuit by reading a schematic Grade: Intermediate students (3-5) Equipment: Magnetic compass (1/pair) Wires with alligator clips (7/pair) Bulb bases (2/pair) 1 large, clear light bulb with filament attached 1 large, clear burned-out light bulb with filament broken scissors (1/pair) Materials: 6 volt lantern battery (1/pair) flashlight screw-in bulbs (2/pair) plus replacement bulbs optional: balloons (1/student) wax paper 2”x2” square folded into a strip (1/pair) keys (1/pair) aluminum foil 2”x2” square folded into a strip (1/pair) shoe laces made only from cloth and plastic (1/pair) cloth ½”x2” strip (1/pair) pencils - wood - sharpened (1/pair) magnets (2/student) tape masking or cellophane (1/pair) coffee straws (10/student) soda straws (10/student) optional: buzzers beepers switches diodes Preparation: Check all batteries and bulbs and replace those that are no longer working. Copy student work sheets, one set per student. It is important that you have replacement bulbs. If the bulbs are not handled carefully, their delicate filaments can break easily. Divide the following “basic materials” which will be needed for all four experiments and place in individual containers or large zip-lock bags: Basic Materials Packet includes: 1 battery 2 bulbs 7 wires with alligator clips 2 bulb bases Supplies needed for Experiment 1: Basic Materials Packet large working clear light bulb large burned-out light bulb Supplies needed for Experiment 2: Basic Materials Packet wax paper 2”x2” square folded into a strip (1/pair) key (1/pair) aluminium foil 2”x2” square folded into a strip (1/pair) shoe laces (1/pair) cloth ½”x2” strip (1/pair) pencil (1/pair) Supplies needed for Experiment 3: Basic Materials Packet tape masking or cellophane (1/pair) magnetic compass magnets (2/student) Supplies needed for Experiment 4: Basic Materials Packet scissors (1/pair) coffee straws (10/student) soda straws (10/student) tape masking or cellophane (1/pair) wax paper 2”x2” square folded into a strip (1/pair) keys (1/pair) aluminium foil 2”x2” square folded into a strip (1/pair) shoe laces (1/pair) pencils (1/pair) replacement bulbs optional materials: buzzers, beepers, switches, diodes Exciting Electricity Experiment 1 Great Idea: Light the Bulb! The Complete Circuit (1 hour) Preparation: In addition to the Basic Material Packet, for Experiment 1 you will need: 1 large clear light bulb with filament attached 1 large clear burned-out light bulb with filament broken Optional - 1 balloon per student Introduction:Electricity is usually invisible. Ask your class to name an example of natural electricity (lightening or the shock created touching a doorknob). Ask your class to name an example of electricity created by humans (light bulbs, TV, walkmans, etc.). Activity: Optional—Pass out one balloon per student. Ask your students to blow up and tie off their balloon. Ask them to explore static electricity with their balloons. By rubbing the balloon on their hair, clothes or rug, they are charging their balloons with static electricity. When charged, they can make the balloon stick on the wall, make their hair stand on end, or stick to their partner. Discussion: We are not able to use the electricity in static electricity. The energy from a single lightening bolt can give off 3,750,000,000,000 kilowatts. That is 3.75 trillion kilowatts! The BPA sells 17,664,000 kilowatts of power every hour. If they could harness lightening, 1 bolt would supply power for the entire Pacific Northwest (Oregon, Washington, Idaho, Montana, Northern California and parts of Alaska) for 15 minutes! There are two types of electricity made by people, AC and DC. AC stands for Alternating Current, the type that your refrigerator uses. DC stands for Direct Current, the types found in batteries. For this series of lessons, we will be using direct current only. Ask your students if they know what types of electricity there are, and an example of each. Electricity cannot be seen, unless something is hooked up to it that resists it, called a resistor. Ask your students to name a resistor (a light bulb or TV). We can make observations about what is happening to the light bulb, and this can help us guess what the electricity is doing. This type of thinking called “building a model.” Activity: Instruct your students to turn to their hand out, Exciting Electricity. Read through the instructions, and ask if everyone understands what they need to do. The first thing to do is to set up the electrical circuit. (Circuit comes from a Latin word that means to go around.) The lights should go on if everything is working. If not, try the following: Trouble Shooters: gently tighten the bulbs check if the circuit is compete check to see if the filament in the bulb is intact check the battery try new light bulbs check that the clips are clipped to metal check that 2 clips are not touching each other You may then either opt to go through the experiments together as a class unit, or instruct your students to work together in their teams. Be sure to encourage discussion, so that the students can brainstorm ideas about what is happening. When everyone has completed the experiment and worksheet, go through the answers, and discuss the observations, then propose the class discussion question. Discussion: Ask your class, “What is the “secret” to making the bulbs light?” Electricity flows like a current of water or wind when there is a complete circuit. To help understand electricity, compare it to water flowing from a high ground to low ground. A more accurate, but not as visual comparison is to air pressure and wind. Air flows from high pressure to low pressure. Electricity flows from the positive terminal (high ground or high pressure) to the negative terminal (low ground). Circuit means circle. The battery “pushes” the electricity from the positive terminal through the wire, to the bulb, through the filament in the bulb to the wire, through the wire, back to the battery at the negative terminal. When it starts, though, everything moves at once, so the bulbs light simultaneously. If the circuit is broken, then the electricity stops “flowing,” and the bulbs go out. Ask student to write what they learned about electricity. Answers to Exciting Electricity Worksheets: 1 2 When did the bulbs light? The light bulb will only light if there is a complete circuit, metal touching metal. Did both bulbs light at exactly the same time? Yes, they do. 3 4 5 6 7 8 9 10 Do you believe that both bulbs actually lit at the same time? This is a subjective question, and can be either yes or no. What happened? Both light bulbs when out. Did both bulbs go out at exactly the same time? Yes, they do. Do you believe that both bulbs actually went out at the same time? This is a subjective question, and can be either yes or no. What happened? Both light bulbs when out. What happened? Both light bulbs stayed out until the metal was touching metal. They did not light until actual contact was made. Do you need actual contact before the bulbs will light? Yes. Draw a picture of the light bulb in the space provided below. Be sure to show the metal tip, the glass globe, and the filament. glass globe filament 11 12 13 14 Can you think of what the filament does in the light bulb? It completes the circuit, so the electricity can continue to flow through the bulb. It is a resistor, so it makes electricity heat up the very thin wire in the glass globe, and that is what glows to make the light. What do you think happens to filament when the light bulb burns out? When the filament is burned-out, the circuit is broken, so electricity cannot flow. The wire cannot heat up without the flow of electricity, so the wire will not glow to produce light. List everything that is needed to make the bulb light. Battery, wires, light bulb with an intact filament. Other answers may include metal base for the bulb, metal clips on the wires. Write down your thoughts from your final classroom discussion (use the back of this page if you need more room). Your final discussion will determine the answers given, although students may come up with other ideas while doing this part of the lesson. Exciting Electricity Experiment 1 Great Idea: Light the Bulb! The Complete Circuit (1 hour) Welcome to the exciting world of electricity! In this experiment, you and your partner(s) will figure out what conditions are necessary for electricity to work. You will also begin to learn the basic symbols used to represent electricity. Before beginning, we need to review your equipment. Please notice that the top end of the battery has two brass springs. If you look at the cardboard top to the battery, the spring near one corner has a (+). This is the positive end of the battery. The spring in the center has a (-) by it, and This is the negative end of the battery. The springs are called terminals. All 7 wires should all have alligator clips attached to them. The round disk is called the bulb base. It will either be all metal, or it will be metal where the bulb is screwed in and have two metal terminals with a plastic or porcelain base. You should also have two small flashlight bulbs. Please notify your teacher if anything is missing. Please be very careful with all your materials. The little bulbs are delicate. Handle them with care. How to set up your equipment for this series of experiments: Screw each bulb into each bulb base. Do not force it or make it too tight. Find three wires. Connect one end of the wire to the positive battery terminal, and the other to one side of the bulb base. Connect the second wire between the 2 bulb bases. Connect the third wire between the bulb base and the negative battery terminal. See the diagram as you work. You can use that as a guide while connecting all your wires, and your equipment should look like the diagram when you are done. 1 When did the bulbs light?________________________________ 2 Did both bulbs light at exactly the same time?________________ 3 Do you believe that both bulbs actually lit at the same time? ____ ____________________________________________________ Break the loop by disconnecting the wire connected to the battery. You only need to disconnect at one point. Leave the wire connected to the bulb base. 4 What happened? ______________________________________ ____________________________________________________ 5 Did both bulbs go out at exactly the same time? ______________ 6 Do you believe that both bulbs actually went out at the same time? ____________________________________________________ Reconnect the wire from the battery holder to the bulb base. Disconnect the wire connecting the two bulb bases. You only need to disconnect at one point, and do not need to disconnect from both bulb bases. 7 What happened? ______________________________________ ____________________________________________________ Slowly bring the clip on the wire to the metal contact point on the bulb base. Carefully watch the distance between the clip and the metal on the base. 8 What happened? ______________________________________ ____________________________________________________ 9 Do you need actual contact before the bulbs will light? _________ Your teacher has 2 big light bulbs, one working and one burned-out. Go look carefully at them. Do you see the wire inside both light bulbs? That is called a filament. Think about what you had to do to make the bulbs light. 10 Draw a picture of the working light bulb in the space provided below. Be sure to show the metal tip, the glass globe, and the filament. 11 Can you think of what the filament does in the light bulb? _______ ____________________________________________________ 12 What do you think happens to filament when the light bulb burns out? 13 List everything that is needed to make the bulb light. _________ ____________________________________________________ 14 Write down your thoughts from your final classroom discussion (use the back of this page if you need more room):________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Exciting Electricity Experiment 2 Stop and Go! Insulators and Conductors (1 hour) Preparation: In addition to the Basic Material Packet, for Experiment 2 you will need to divide the following materials and place in individual containers or small zip-lock bags: wax paper 2”x2” square folded into a strip (1/pair) keys (1/pair) aluminum foil 2”x2” square folded into a strip (1/pair) shoe laces (1/pair) cloth ½”x2” (1/pair) pencils (1/pair) Introduction:Some materials allow electricity to flow, and therefore, complete the circuit. These materials are called Conductors. Some materials stop the electricity from flowing, and therefore break the circuit. These materials are called Insulators. Ask your students to define the words conductor and insulator. Ask how these two words could apply to electricity. Activity: Instruct your students to turn to the hand out, Stop and Go!. Read through the instructions, and ask if everyone understands what they need to do. The first thing to do is to set up the electrical circuit. (Circuit comes from a Latin word that means to go around.) The lights should go on if everything is working. If not, try the following: Trouble Shooters: gently tighten the bulbs check if the circuit is compete check to see if the filament in the bulb is intact check the battery try new light bulbs check that the clips are clipped to metal check that 2 clips are not touching each other You may then either opt to go through the experiments together as a class unit, or instruct your students to work together in their teams. Be sure to encourage discussion, so that the students can brainstorm ideas about what is happening. When everyone has completed the experiment and worksheet, go through the answers, and discuss the observations, then propose the class discussion questions. Discussion: Ask your class, “What is an insulator? What is a conductor?” An insulator is any material, when joined to the circuit, that prevents the light bulb from lighting (or any other type of resistor from working). It prevents the passage of electricity. “A non-conducting substance or body, as porcelain or glass, used in insulating wires, etc.” Webster's Collegiate Dictionary, 5th Edition. A conductor is any material, when joined to the circuit, that permits the light bulb to light (or any other type of resister to work). It allows the passage of electricity. “A substance or body capable of readily transmitting electricity, heat, or the like.” Webster's Collegiate Dictionary, 5th Edition. Ask your class, “What do you need for an electrical circuit? List all the components (parts) and the materials from which they are made. Why is it important that some materials are insulators?” An electrical circuit needs a power source (battery), wires, with conductors on the inside and insulators on the outside, resistors so we know that electricity is actually flowing (sometimes we can tell because the battery or wires will get hot). Conductors are usually metal, and insulators are usually plastic or glass. If there were no insulators, we would get shocked, and we would not be able to use the electricity. It would be too dangerous. Also, insulators direct the electricity to where we want it to go. Without it, we might never get the light bulb to light, because we could too easily create “short circuit”, or a path around the resistor. Ask your class, “Why do you think people use electrical schematics?” A schematic is an abstract drawing that is easy to read. It can tell you how your house is wired. An electrical engineer can design a complex electrical system for the Space Shuttle by using the same symbols. If something doesn’t work, or breaks, it is easy to go back, see what was done, and how to test it. Answers to Stop and Go Worksheets: 1 2 Did your bulb light? This is to help students trouble shoot before they begin the experiments. Students fill out table (answers on next page). Students predictions and answers for “Other” will vary. Test Object Prediction Insulator or Conductor Observation Lit or not lit lit Actual Insulator or Conductor conductor not lit insulator lit conductor Shoe Lace not lit insulator Pencil Wood not lit insulator Pencil “lead” lit conductor Pencil metal band lit conductor not lit insulator Key Waxed Paper Aluminum Foil Clothing Other Other 3 4 5 What do you notice about conductors? (What is something that they all have in common?) Most conductors are made of metal. The pencil “led” is actually made from graphite, which is carbon based, and non metallic. It is only modest conductor compared to the metal band on the pencil. What do you notice about insulators? (What is something that they all have in common?) Most insulators are made from non-metallic materials, like plastic, glass, and cloth. The schematic drawing is below. + - battery wires resistor resistor 6 Write down your thoughts from your final classroom discussion Your final discussion will determine the answers given, although students may come up with other ideas while doing this part of the lesson. Exciting Electricity Experiment 2 Stop and Go! Insulators and Conductors (1 hour) In this experiment, you and your partner(s) will figure out what materials allow electricity to flow, (called conductors) and what materials stop the electricity from flowing (called insulators). Before beginning, we need to review your equipment. Please notice that the top end of the battery has two brass springs. If you look at the cardboard top to the battery, the spring near one corner has a (+). This is the positive end of the battery. The spring in the center has a (-) by it, and This is the negative end of the battery. The springs are called terminals. All 7 wires should all have alligator clips attached to them. The round disk is called the bulb base. It will either be all metal, or it will be metal where the bulb is screwed in and have two metal terminals with a plastic or porcelain base. You should also have two small flashlight bulbs. Check the filaments. Please notify your teacher if anything is missing. Please be very careful with all your materials. The little bulbs are delicate. Handle them with care. How to set up your equipment for this series of experiments: Screw each bulb into each bulb base. Do not force it or make it too tight. Find four wires. Connect one end of the wire to the positive battery terminal, and the other to one side of the bulb base. Connect the second wire from the bulb base to another wire. Connect the third wire from the wire (alligator clip to alligator clip) to the other bulb base. Connect the fourth wire between the bulb base and the negative battery terminal. See the diagram as you work. Your wires, and your equipment should look like the diagram when you are done. 1 Did your bulb light? ____________________________________ You and your partner(s) will be testing a variety of materials. In order to test them, you will need to break your circuit (remember, that is the circle of electricity from the last experiment) between the two wires that are clipped together (alligator clip to alligator clip) and put the material into the circuit by clipping the 2 free alligator clips to it. You will have a bulb on both sides, so you will know for certain if there is any electricity flowing, or if it has been stopped. Take each of the test objects and write down in the Prediction column what you think will be an insulator (the bulbs will not light), or a conductor (the bulbs will light). Unclip the two alligator clips and clip both to the test object. Be sure the clips are not touching each other. In the Observation column, record if the bulbs lit or if they were not lit. In the Actual column, record whether the test object is an insulator or a conductor. The last items on the list are “other.” That is for you and your partner to select items and test to see if they are conductors or insulators. Be sure to write what the items are. 2 Test Object Key Waxed Paper Aluminum Foil Shoe Lace Pencil Wood Pencil “lead” Pencil metal band Clothing Other Other Prediction Observation Actual Insulator or Conductor Lit or not lit Insulator or Conductor 3 What do you notice about conductors? (What is something that they all have in common?) ____________________________________ _____________________________________________________ 4 What do you notice about insulators? (What is something that they all have in common?) ____________________________________ Next, we are going to learn how to draw a real electrical diagram, called a schematic. You will need to learn some symbols first. + 1 battery 5 + 3 batteries Bulb not lit Bulb lit Wires Using the diagram, replace the pictures of the batteries and bulbs with the symbols for the batteries and bulbs and wires to create a schematic. (Notice the + end of the battery is a long thin line, and the - end of the battery is a short thick line.) Use the space below. Write down your thoughts from your final classroom discussion, and what you have learned about electricity so far. ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ TEAM CHALLENGE: Work with another team, so there are at least four people. Create circuits from the following schematics. Observe the brightness of the bulbs each time you add one, and then finally, when you add an additional battery: Exciting Electricity Experiment 3 The Magic Moving Magnetic Needle Electromagnetism (1 hour) Preparation: In addition to the Basic Material Packet, for Experiment 3 you will need to have 4 magnets and a magnetic compass for each pair of students. Before class begins, use the compass to find north in your classroom. Introduction:Electricity sets up a magnetic field perpendicular to the flow of electricity. This is a simple introduction to this phenomenon, and it is not necessary for the student at this time to understand anything more than there is a connection between the two. Ask how many students have used compasses before. Ask which way the red needle points (magnetic north). Remind them to check that their needle is moving freely. It may get stuck. A light tap on the bottom usually corrects this problem. They need to hold their compass flat in their palm, or put it down on a table or the floor before reading it. Activity: Instruct your students to turn to the hand out, The Magic Moving Magnetic Needle. Read through the instructions, and ask if everyone understands what they need to do. The first thing to do is to set up the electrical circuit. (Circuit comes from a Latin word that means to go around.) The lights should go on if everything is working. If not, try the following: Trouble Shooters: gently tighten the bulbs check if the circuit is compete check to see if the filament in the bulb is intact check the battery try new light bulbs check that the clips are clipped to metal check that 2 clips are not touching each other You may then either opt to go through the experiments together as a class unit, or instruct your students to work together in their teams. Be sure to encourage discussion, so that the students can brainstorm ideas about what is happening. When everyone has completed the experiment and worksheet, go through the answers, and discuss the observations, then propose the class discussion questions. Discussion: Ask your class, “What do you think is happening to make the magnetic needle move? Why do you think it changes directions when the battery is reversed?” This is an advanced concept in the study of electromagnetism, and encourage the class to brainstorm any ideas that they may have why the magnetic needle is moving. There is a correlation between the forces in electricity and magnetism. They are perpendicular to each other. Depending on the volts (the electrical force) the magnetic needle will move anywhere between 1º to 90° from the wire carrying the electricity. The greater the volts, the more the magnetic needle will move. The magnetic needle moves away from the flow of electricity through the wires. Because of this phenomenon, we can create electricity by moving a magnet through coiled wires with a force. For instance, the turbines at the Bonneville Dam are made up of huge magnets and coiled wires. The force of water moves the magnets around the coiled wires creating electricity. Answers to The Magic Moving Magnetic Needle Worksheets: 1 Where in your classroom does the red needle point? Students should name the wall or object that is located in the north part of your classroom. 2 Move to another area in your classroom. Face a different direction. Where does the red needle point? As before, the needle will point to the same spot, the north wall or an object on the north wall of your classroom. 3 Move to a third area in your classroom. Face a different direction. Where does the red needle point? As before, the needle will point to the same spot, the north wall or an object on the north wall of your classroom. 4 What do you notice about the magnetic compass needle? No matter which way the student is facing, it will always point in the same direction or spot. 5 Did your bulb light? This is to help students trouble shoot before they begin the experiments. 6 What was the magnetic needle doing before you reconnected the circuit? It was pointing north or towards the north facing wall, or towards an object on the north wall of your classroom. 7 What happened to the magnetic needle after you reconnected the wires of your circuit? The magnetic needle moved away from the north facing wall. Depending on how the students orient the compass in relationship to the circuit, it will move either towards the west or the east. 8 What was the magnetic needle doing before you reconnected the circuit? It was pointing north or towards the north facing wall, or towards an object on the north wall of your classroom. 9 What happened to the magnetic needle after you reconnected the wires of your circuit? Once again, the magnetic needle moved away from the north facing 10 11 12 13 wall. Depending on how the students orient the compass in relationship to the circuit, it will move either towards the west or the east, but it should move in the same direction that it did the first time. Does the needle move in the same direction each time? Yes it does. Does the magnetic needle move? Yes it does. Does it move in the same direction that it did before you reversed the direction of the battery holder? No, it moved in the opposite direction as the first and second time, before the battery was reversed. In the space provided below, draw a schematic of the circuit you have created. + - battery wires resistor 14 resistor Write down your thoughts from your final classroom discussion, and what you have learned about electricity so far. Your final discussion will determine the answers given, although students may come up with other ideas while doing this part of the lesson. Exciting Electricity Experiment 3 The Magic Moving Magnetic Needle! Electromagnitism (1 hour) In this experiment, you will discover some “magic” with electricity! Remember, the current “flows” through the wires when you have an electrical circuit. When there is an electrical current, it also creates a magnetic force! That means, it creates a force just like a magnet does. Magnets are fun to play with, and they are amazing. Magnets are special materials (usually metals) that act like magic. Sometimes they stick together (attract), and sometimes they push each other apart (repel). Spend some time exploring the properties of magnets. Magnetic compasses to help us find our way in the woods. A magnetic compass is made up of a plastic case and inside, a freely moving red metal needle. The needle is magnetized. It will point to the magnetic north. When studying electricity, we can also use a compass to observe that something happens when a current goes near the compass needle. You will find out! The compass must remain flat and the needle move freely. Before we begin our experiment, we are going to explore your compass. Take your compass and set it on the table. Answer the following questions: 1 Where in your classroom does the red needle point? __________ ____________________________________________________ 2 Move to another area in your classroom. Face a different direction. Where does the red needle point? _________________________ 3 Move to a third area in your classroom. Face a different direction. Where does the red needle point? _________________________ 4 What do you notice about the magnetic compass needle? ______ ____________________________________________________ Before beginning, we need to review your equipment. Please notice that the top end of the battery has two brass springs. If you look at the cardboard top to the battery, the spring near one corner has a (+). This is the positive end of the battery. The spring in the center has a (-) by it, and This is the negative end of the battery. The springs are called terminals. All 7 wires should all have alligator clips attached to them. The round disk is called the bulb base. It will either be all metal, or it will be metal where the bulb is screwed in and have two metal terminals with a plastic or porcelain base. You should also have two small flashlight bulbs. Check the filaments. Please notify your teacher if anything is missing. Please be very careful with all your materials. The little bulbs are delicate. Handle them with care. How to set up your equipment for this series of experiments: Screw each bulb into each bulb base. Do not force it or make it too tight. Find three wires. Connect one end of the wire to the positive battery terminal, and the other to one side of the bulb base. Connect the second wire between the two bulb bases. Connect the third wire from the bulb base to the negative battery terminal. Refer to the drawing on your diagram. You can use that as a guide while connecting all your wires. 5 Did your bulb light? ____________________________________ It is important in this experiment that you do not move any part of the circuit unless you are instructed to do so. Tape the three wires near the alligator clips, but leave an inch or so to connect and disconnect your circuit. This will help you to be sure that you do not move them. Be sure that your wires are straight. If there are any loops in them, you may misread the results. Disconnect your circuit anywhere. Place your magnetic compass under the wire leading from the battery holder to the first bulb. Reconnect your circuit. 6 What was the magnetic needle doing before you reconnected the circuit? ______________________________________________ 7 What happened to the magnetic needle after you reconnected the wires of your circuit? ___________________________________ ____________________________________________________ Disconnect your circuit. Put the magnetic compass under the wire between the two bulbs. Reconnect the circuit. 8 What was the magnetic needle doing before you reconnected the circuit? ______________________________________________ 9 What happened to the magnetic needle after you reconnected the wires of your circuit? ___________________________________ ____________________________________________________ 10 Does the needle move in the same direction each time? _______ Keep your circuit exactly the way it is. Carefully unclip your battery holder at both ends. Turn it around, so that the + end of the battery holder is now clipped to the wire that was clipped to the - end of the battery holder, and the - end of the battery holder is now clipped to the wire that was clipped to the + end of the battery holder. The rest of your circuit should not be moved. Leave it taped to your desk or table. Just reverse the battery. Be sure that the magnetic compass is still in position. Reconnect your circuit. 11 Does the magnetic needle move? _________________________ 12 Does it move in the same direction that it did before you reversed the direction of the battery holder? ___________________________ 13 In the space provided below, draw a schematic of the circuit you have created. Included is the picture we will use for the compass. The symbols are: + 1 Battery 14 + 3 Batteries Magnetic Compass Bulb not lit Bulb lit Wires Write down your thoughts from your final classroom discussion, and what you have learned about electricity so far. ______________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ ____________________________________________________ Exciting Electricity Experiment 4 Circuit Circus Simple, Series and Parallel Circuits (1 hour) Preparation: In addition to the Basic Material Packet (note, all 7 wires will be needed), for Experiment 4 you will need to use the materials from Experiment 2 that are in containers or small zip-lock bags: wax paper 2”x2” square folded into a strip (1/pair) keys (1/pair) aluminum foil 2”x2” square folded into a strip (1/pair) shoe laces (1/pair) cloth ½”x2” (1/pair) pencils (1/pair) coffee straws (10/student) soda straws (10/student) scissors (1/pair) and optional materials (for class challenge): buzzers, beepers, switches, diodes (only work one way. When hooked up incorrectly, they will not light. Reverse the clips, and they will work.) Introduction:In this Experiment, students will be using all the knowledge that they have learned so far. By reading the schematics, they will construct a simple, series and parallel circuit. After completing each type of circuit, they will build a short circuit. Then, to better understand how electricity flows through the wires (the current), they will model with straws. Finally, they will be given the ultimate class challenge! Activity: Instruct your students to turn to the hand out, Circuit Circus. Read through the instructions, and ask if everyone understands what they need to do. The first thing to do is to set up the electrical circuit. (Circuit comes from a Latin word that means to go around.) The lights should go on if everything is working. If not, try the following: Trouble Shooters: gently tighten the bulbs check if the circuit is compete check to see if the filament in the bulb is intact check the battery try new light bulbs check that the clips are clipped to metal check that 2 clips are not touching each other You may then either opt to go through the experiments together as a class unit, or instruct your students to work together in their teams. Be sure to encourage discussion, so that the students can brainstorm ideas about what is happening. When everyone has completed the experiment and worksheet, go through the answers, and discuss the observations, then propose the class discussion questions. Challenge: Instruct the students to push all the desks or tables into the center of the room. Gather all the batteries on one desk. Have the students, working as a class, construct a huge circuit using resistors in both series and parallel. Each pair must include at least one conductor and two resistors in their portion of the circuit. They cannot complete the circuit by themselves, because they do not have a battery. When everyone is ready with their individual portion, they connect it to their neighbors. Continue this process until everyone has connected together, and when the batteries are added, the circuit will be complete. Begin adding one battery at a time until at least one resistor begins to work. You can connect the batteries by using additional wires between. Be sure to connect the negative terminal on one battery to the positive terminal on the next battery. If you connect a negative to a negative, it just won’t work. How many batteries does it take? Instruct them to continue adding one battery at a time until all resistors are working. How many batteries are needed until all the resistors are working? Have each pair develop a schematic of their portion of the circuit. If all the papers were placed in order, the schematic would represent the circuit the class just created. You will need to prepare the schematic of the batteries, or you may assign that to a team if they complete their schematic before others. Have the students dismantle their class challenge circuit and put all the pieces away. When everything has been put away, have the class arrange their portion of the circuit schematic so that it represents the class circuit. With the papers, create the completed class schematic. Extensions of this activity would be to mix up the schematics, pass them out, and have the class predict if it would be a complete circuit. Have the build their portion of the circuit schematic, attach it all together to test. Does it take the same number of batteries for all the resistors to work? Have each student in the class draw a different assigned schematic (for instance, one team is assigned a parallel circuit with two conductors and one resistor, one team is assigned a series circuit with 5 resistors, etc., then put the circuit together. Does it work? Have the class design a crazy circuit, using materials other than the wires. Be careful if you use steel wool; it has been know to catch fire! Answers to Circuit Circus Worksheets: 1 Did your bulb light? This is to help students trouble shoot before they begin the experiments. 2 What happened? Both lights go out. 3 Did both bulbs go out at exactly the same time? Yes. 4 What do you think would happen if one bulb went out on the old Christmas tree lights? All the lights would go out, too. 5 Did both bulbs light at exactly the same time? Yes. 6 What happened? Both light bulbs went out. 7 What happened? Only one light bulb went out, resistor A. The light bulb at resistor B stayed on. 8 What happened? Only one light bulb went out, resistor B. The light bulb at resistor A stayed on. 9 Why do you think your home is wired in parallel? One reason our homes are wired in parallel is so every time a light bulb burns out, all the other light bulbs will stay lit. 10 What happened? The light bulb at resistor B when out, although there was a complete parallel circuit. 11 Which model is harder to blow air through? Most people think that the long straw is harder to blow through. 12 Which model has more air coming through? Most people think that more air is able to come through the bunch of straws. 13 What is different? It is much harder to blow air through the straw, and the air is not going out the end of the straw, but through the cut. 14 What do you notice about how hard it is to blow and how much air comes out of the straw. Instead of the air coming out the end of the straw, it is taking a short cut through the cut in the straw. With the long straw, this is very obvious, since most of the air is diverted through the cut. With the bunch of straws, most of the air continues to travel through the other, unaffected straws. 15 16 17 18 Ideas to wrap up the electricity unit are: Go on a field trip to a dam or other electricity producing facility. Invite someone who works for the electric company to talk. Research and recreate what it would be like to live without electricity. Invite OMSI out to present a class. Exciting Electricity Experiment 4 Circuit Circus! Simple, Series and Parallel Circuits (1 hour) In the final experiment on electricity, you will be building circuits from schematics, making a short circuit, modeling the electrical current with straws, and finally, participating in the CLASSROOM CHALLENGE!!!! Before beginning, we need to review your equipment. Please notice that the top end of the battery has two brass springs. If you look at the cardboard top to the battery, the spring near one corner has a (+). This is the positive end of the battery. The spring in the center has a (-) by it, and This is the negative end of the battery. The springs are called terminals. All 7 wires should all have alligator clips attached to them. The round disk is called the bulb base. It will either be all metal, or it will be metal where the bulb is screwed in and have two metal terminals with a plastic or porcelain base. You should also have two small flashlight bulbs. Check the filaments. Please notify your teacher if anything is missing. Please be very careful with all your materials. The little bulbs are delicate. Handle them with care. How to set up your equipment for this series of experiments: Read this schematic. Note, it is different than other circuits you have prepared. 1 Did your bulb light? ____________________________________ This is a simple circuit. Simple circuits are used in flashlights. We will begin to use a new symbol for a resistor, can be anything from a light bulb to a radio. since a resistor Construct the next circuit using the following schematic: This is a circuit in series. To help you remember it, one light bulb follows another, like a series of movies or a series of books. This is another circuit you have been building since the first experiment. Break the loop by disconnecting the wire connected to the battery holder . You only need to disconnect at one point. Leave the wire connected to the bulb base. 2 What happened? ______________________________________ ____________________________________________________ 3 Did both bulbs go out at exactly the same time? ______________ This is an important feature of circuits in series. One example of this type of wiring is found in the old Christmas tree lights. 4 What do you think would happen if one bulb went out on the old Christmas tree lights? ___________________________________ The last circuit you will build is different than any you have built before. Take your time, read the schematic carefully. You can do it! You will need 6 of your wires to build this circuit. 1 2 resistor A 3 4 5 6 resistor B Hint: The wires are numbered. This circuit is in parallel. As you can see, the resistors are parallel to each other. This is the way your home is wired for electricity. Answer the following questions to figure out why. 5 Did both bulbs light at exactly the same time?________________ Break the circuit by disconnecting the wire #2 connected to the battery. 6 What happened? ______________________________________ ____________________________________________________ Reconnect wire #2 from the battery to the bulb base. Disconnect wire #4 at resistor A’s bulb base. 7 What happened? ______________________________________ ____________________________________________________ Reconnect wire #4 at resistor A’s bulb base. Disconnect wire #6 at resistor B’s bulb base. 8 What happened? ______________________________________ 9 Why do you think your home is wired in parallel? _____________ ____________________________________________________ Using the circuit in parallel, add your 7th wire from point 1 to point 2. Point 1 resistor A resistor B Point 2 10 What happened? ______________________________________ ____________________________________________________ Electricity is lazy. It will find the path of least resistance. It must be hard work going through resistors, because if electricity can take a short cut around a resistor, it will. To help understand what is going on with the electricity, you will use straws and air as models. You will each need 5 coffee straws, 5 soda straws, tape, and scissors. You and your partner will be making your own model, because you will be blowing into them. First, tape 5 soda straws end to end, to make one really long straw. Second, tape 5 coffee straws in a bunch, with the ends all lined up evenly. Blow on the long straw. Notice how hard it is to blow. Have your partner feel how much air is coming through the straw. Next, blow on the bunched straws. Notice how hard it is to blow. Have your partner feel how much air is coming through the straws. Now switch with your partner, so you can feel the air flow. Answer the following questions. 11 Which model is harder to blow air through?__________________ 12 Which model has more air coming though?__________________ The long straw represents a circuit in series. In series, the electricity flows through each and every part of the circuit, and it flows at the same rate in every part it passes through. The bunch of straws represent a circuit in parallel. In parallel, the electricity forks, and only part of the charge travels through each branch. With the scissors, cut a notch in one of the individual straws on the long straw. Don’t cut the straw in two. Cut a notch in one of the straws (but only one) on the bunched straws. Don’t cut the straw the straw in two. Blow into each of the models, long and bunched, while your partner feels how much air comes through. Notice how hard it is to blow. Switch places with your partner. 13 What is different? _____________________________________ 14 What do you notice about how hard it is to blow and how much air comes out of the straw. _________________________________ ____________________________________________________ ____________________________________________________ The cuts in the straws represent a short circuit. As you can feel, most of the air takes a short cut through the cut in the straw in the long straw, but air continues to flow through the bunched straws. The final project in this experiment is the CLASSROOM CHALLENGE. Your teacher will explain the challenge when everyone is ready. Exciting Electricity Experiment 5 Curious Circuit Take home project (1 hour) This activity is to allow students time to explore what they have learned by allowing them to apply a practical application to a set problem. Throughout this series, the students have been gaining a fundamental understanding of models of electricity, and applying those models to what they have observed electricity actually doing in a circuit. They probably have enough sophistication now to work through this activity with very little problem-solving from you. There is some expense to this project, but the results are well worth the expense. Your students will be making a simple circuit board, and creating a game. The game can be of their own choosing, or you could instruct them to create a “trivial pursuit” game testing their knowledge of electricity. Curious Circuits Advanced Electricity Objectives: Students will Learn that an electrical current needs to make a complete circuit Explore circuitry Make a circuitry game Grades: 2nd-6th with modifications Time: prep time 60 minutes for younger students, 10 minutes for older students, and 60-90 minutes for the activity Materials: 2 pieces heavy (Bristol) paper / student 1 piece regular paper / student 1 9 volt battery / student 1 small Christmas tree light / student 1 pen or pencil / student 3-6 strips aluminum foil / student 1”x12” (depending on age) 1 glue stick / student 1 insulated wire 18” / student masking tape 1 / 2-4 students 1 hole punch / 2-4 students For Older Students: 1 wire stripper / 2-4 students 1 ruler / 2-4 students Preparation: Gather all materials For younger students, you will need to prepare the battery, light and wires for them. Follow the directions 1-9 in the activity section for each of your students. Activity: For older students, this part of the activity works best if you talk the students through very carefully. Each person should have a partner, and the partner will help with one, then get help with the other. 1. Measure insulated wire and cut into one 4” piece and two 7” pieces. 2. Strip about 1” of insulation off each end of the 3 pieces of wire. 3. Curl the exposed 4” wire around the negative terminal of the 9 volt battery. If it won’t stay on, use a little electrical or masking tape to hold that wire in place. 4. Curl one of the 7” exposed wires around the positive end of the 9 volt battery. 5. On the 7” wire that is not on the battery, make a hook on one end of the exposed wire. 6. On the 4” wire that is attached to the negative end of the battery, make a hook on the exposed wire on the free end. 7. Carefully pull the two delicate wires on the Christmas tree light away from the plastic base. Carefully loop the wire, so it will hook onto the two wire hooks that were created from the 4” and 7” wires. 8. Test the Christmas tree light. It is a diode. Diodes work only if electricity “flows” in the correct direction, so you will need to test which side of the light needs to hook to the 4” wire. 9. Hook the light to the correct wires, and tape them down securely onto the 9 volt battery. Wire taped down on both sides of the light. Terminals The students are now ready to make their circuit game. Pass out all the materials, (for younger students, this includes the battery/wire/light portion that you did for them. Tell the students that they will be creating a circuit board game. Review electricity (must make a complete circle, if the resistor doesn’t work, there must be a break or a short in the circuit, insulators and conductors, etc.) For younger students, limit the number of circuits to 3. As the students become more sophisticated, add additional circuits. Direct the student to make 3 (or more) equal distanced hole punches on one side of the heavy (Bristol) paper, and an equal number of hole punches on the other side of the paper also at equal distances. The students then glue on strip of aluminum foil down so that it covers one of the 3 holes on the left side of the paper, and one of the three holes on the right side of the paper. (Tell them that only one can be directly across for the other.) To insulate the foil, cut a strip of regular paper about 1½” wide and as long as the foil, and glue that paper strip over the foil. Repeat the above procedure for the other holes until all of the holes on one side of the paper, have foil that lead to the holes on the other side of the paper. Then, glue to other heavy (Bristol) paper over the back of the circuits to hide them. Tape the battery/light/wire unit to the middle of the paper. Number each hole on the left side of the paper, and alphabetize the holes on the right. On a scrap piece of paper, match the number to the letter that lights the Christmas tree light when the exposed wire on the 2 loose battery wires touch the aluminum foil of those two holes. For instance, 1 + c, 2 + a, 3 + b. The students can now create a game. They can be questions and answers on electricity, or other science topics, the joke on one side and the punch line on the other side, are two examples for creating a game. Wrap up: Discuss how homes and schools are wired.