Georgia Performance Standards Framework for Physical Science 8 th Grade. Powering Satellites

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1 The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples of Student Work, and Teacher Commentary. Many more GaDOE approved instructional plans are available by using the Search Standards feature located on GeorgiaStandards.Org. Georgia Performance Standards Framework for Physical Science 8 th Grade Subject Area: Physical Science Grade: 8 Powering Satellites Standards (Content and Characteristics): S8P5. Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature. a. Recognize that every object exerts gravitational force on every other object and that the force exerted depends on how much mass the objects have and how far apart they are. b. Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer energy. Enduring Understanding: Energy is the ability to do work. Without energy, forces cannot be generated to make things move or change Energy exists in two primary forms. Potential energy is stored energy that has the potential to do work. Like charges repel while opposite charges attract. Insulators resist the movement of charges while conductors allow charges to move easily. Closed circuits allow current to flow while open circuits have a broken path preventing the movement of charges. All matter is composed of positive and negative particles. The movement of the charges created by these particles is what we call an electric current. The sun is the ultimate source of energy on Earth. This energy is changed into many forms that all plants and animals use to do work. Essential Questions: Why do batteries die? Do larger batteries produce more current? August 13, 2008 Page 1 of 12

2 Pre-Assessment: ADMINISTRATION PROCEDURES KWL Ask students to list any information they know about electricity and batteries. Ask students what they would like to know more about; and what they expect to learn. Outcome / Performance Expectations: Students will build a simple battery and test its voltage and current using a multi-meter in a simple series circuit. Students will connect batteries in series to measure effects of combining batteries in series. Students will mass the batteries, calculate the power produced by the cells to compare and contrast the efficiency of the benefits of using batteries and solar panels. General Teacher Instructions: Divide students into groups of two to three members. Stations may be used if supplies are limited. Individual ammeters or voltmeters may be used if multi-meters are unavailable. Pre-mark all batteries, panels, and batteries. Low voltage LED s may replace the motor. Make sure Current is tested in series! LARGER ELECTRODES (more surface area) will yield better results. Make sure Current is tested in series! (You can ensure it is in series if you have the student connect the circuit first and then BREAK the circuit to insert the two ends of the ammeter into the circuit. Using a multimeter with a fuse can help prevent costly mistakes.) All equipment can be located at your local electronics store, i.e. Radio Shack, except for the lemons. Explore current and voltage by connecting multiple batteries or photovoltaic cells in series. August 13, 2008 Page 2 of 12

3 Materials Needed: Safety Precautions: Task with Student Directions: 2 Lemons 2 AA batteries 2 D cell batteries 2 Photovoltaic cells Copper electrodes (copper wire) Zinc electrodes (galvanized nail) Multimeter (able to measure DC and low current) small DC motor or Low voltage LED Standard safety procedures are to be followed. VOLTAGE in our homes is much greater. Do not try this at home. Do not allow students to connect a wire directly between the terminals of the battery, it may cause the battery or wire to overheat and/or explode. See attached Resources: Homework / Extension: You are an astronaut on the International space station. You have lost all power due to battery failure. You have access to solar panels to recharge the batteries, but you must connect them into the circuit in such a way to allow the batteries to recharge. August 13, 2008 Page 3 of 12

4 Background: Powering Satellites Batteries are used daily in our lives to produce a source of electric energy (batteries store energy not current perhaps this needs to go in the misconceptions area of framework. Voltage is related to energy. The current that exists in a circuit depends on the battery AND what is connected to the battery, including how fresh the battery is (internal resistance) when we do not have access to an electrical outlet, or we need a source of current on the go. However, batteries tend to be a very inefficient source of energy, as we put more energy into creating them than we get back out. Batteries also tend to be large and heavy when we need large amounts of electricity. These two factors are primary reasons that many satellites use solar panels to provide power for the bulk of their operations in space and only use batteries to store energy for reserves. But what is a battery? Simply put, a battery is a storage device that contains two conducting metals (electrodes) and a solution (electrolyte). When the metals are immersed into the solution, a chemical reaction takes place causing charges to be displaced. These charged particles have potential energy and this energy can be used to do work. The energy of the charged particles is called voltage (V). If the two electrodes are connected by a conductor, the charges will flow through the conductor and allow the energy carried by the charges to do work. This is called an electric current (I) and is measured in units called amperes; amps for short. The more current flowing through a battery and through the circuit connected to the battery, the faster the battery will run down/lose its ability to do work on charges. Batteries come in many shapes, sizes, voltages, and storage sizes to accommodate the various needs of the devices they power. Normally the more current needed the larger the battery. However, some batteries such as D, C, AA, and AAA cells have the same potential energy, but vary in size to last longer when used by certain devices. Solar panels capture this energy emitted by the sun and convert it to electrical energy. Tiny particles of sunlight bombard special panels that are sandwiched together. The result is an electric current that can be used to do work. August 13, 2008 Page 4 of 12

5 Mission: One Stop Shop For Educators NASA is building a series of satellites to replace many of its older satellites with satellites that are more modern and can do more missions. However, a tragic event has destroyed most of their battery and solar panel research. To assist them in rebuilding their database of research, your school has been chosen to do research to determine voltages and currents produced by batteries and solar panels. This information will be used to determine if replacing batteries with solar panels is a practical solution for the new model satellites. Materials: Multi-meter 3 jumpers with clips 2 Galvanized nails (or paper clips) 2 Copper wires (or pennies) 2 Lemons 2 D cell batteries 2 AA cell batteries 2 small solar panels Permanent marker Masking tape small DC motor Low voltage LED (a small DC motor works well if a low voltage LED is not available) August 13, 2008 Page 5 of 12

6 Preliminary Question: 1. Energy that we use on Earth comes primarily from the Sun. Fossil fuels are remains of life that lived on our planet many years ago. Batteries use electrodes and an electrolyte to produce an electric current. These are composed of elements that are found in various parts of the Earth. Where and how do you think these elements originated? Overview: Students will build a dry cell and a wet cell to measure the voltage (V) and current (I) using a multi-meter in a simple circuit. A solar panel will also be used to measure voltage and current for comparison. Students will connect batteries in series to measure effects of combining batteries in series. Students will mass the batteries, calculate the power produced by the cells to compare and contrast the efficiency of the benefits of using batteries and solar panels. Students will calculate the Power delivered by a voltage source, P = I x V. Power is measured in watts. Directions: 1. With the marker, label the lemons as A and B. Now label the D cells A and B. Mark the AA cells as A and B. Finally, mark the back of the solar panels. Mass the lemons and all batteries. Record these in your data table. 2. Roll your lemons on the table to loosen the juice. Be careful not to burst your lemon. 3. Push a nail into lemon A making sure to insert it no farther than half way into the lemon. Now about an inch away from the nail, insert the copper wire. See figure 1 4. Next, connect an alligator clip to each electrode. 5. Set your multi-meter to the appropriate setting to read DC voltage. Using the multi-meter connect one probe to each clip. Read and record the voltage. Now move the indicator switch to measure current. (copper-red, nail-black) 6. Attach the motor to either alligator clip. Complete the circuit with the probes. Read and recorded the current. See figure 2 7. Now repeat the steps two through six with the lemon B. Be sure to record your data and record. August 13, 2008 Page 6 of 12

7 8. Remove the motor and remove the clip from the nail on lemon B. Now connect the nails on lemon A and B using a jumper with one alligator clip on each nail. Attach the multi-meter to the two free clips and record the voltage. See figure 3 9. Now disconnect all jumpers from lemon B. Now attach nail from A to copper wire on B. Attach a separate clip to the nail on B. Now check the voltage. Attach the motor and check the current. 10. Next use the probes to measure the voltage of the D cell battery. To do so, place the red probe end to the positive pole (+) of the battery and the black probe to the negative pole (-). Measure both voltage and current and record. 11. Repeat step 10 with the AA battery, record the voltage. Attach the motor and record the current. 12. Now place the two + poles of the D cell batteries together and tape the batteries in place. Place the red probe on one end of the batteries and the black probe on the opposite. Record the voltage. Attach the motor and measure the current. 13. Separate the batteries and place the + pole of the first battery to the pole of the second battery. Tape to hold in place. Use the probes to measure the voltage. Attach the motor and measure the current. Record. 14. Next repeat using the two AA batteries. 15. Almost finally, connect the alligator clips to the wires from panel A. Then connect the clips to the probes of the multi-meter. Record the voltage. Do the same with panel B. 16. NOW FINALLY, connect the panels together and measure the voltage. Figure 1 August 13, 2008 Page 7 of 12

8 Figure 2 One Stop Shop For Educators Figure 3 August 13, 2008 Page 8 of 12

9 Lemon Data table: Mass (grams) Voltage (volts) Current (amps) P = I x V (watts) A B Circuit 1 Circuit 2 D cell Data table: Mass (grams) Voltage (volts) Current (amps) P = I x V (watts) A B Circuit 1 Circuit 2 AA cell Data table: Mass (grams) Voltage (volts) Current (amps) P = I x V (watts) A B Circuit 1 Circuit 2 August 13, 2008 Page 9 of 12

10 Solar panel Data table: Mass (grams) Voltage (volts) Current (amps) P = I x V (watts) A B Circuit 1 Circuit 2 Calculations and Conclusions: 1. A small flash light uses two AA batteries to light the bulb. Based on this information, could two lemon batteries illuminate a flashlight? What about the solar panels (Sounds silly using solar panels to light a flashlight)? Explain your reasoning. 2. Larger flashlights use D cell batteries to light a bulb. Compare the voltage and the amperage of the D and AA batteries and state a hypothesis as to why large flashlights use larger batteries instead of smaller ones. What evidence would be used to support or reject your hypothesis? August 13, 2008 Page 10 of 12

11 3. When the batteries were connected at the same pole, what did you observe? Why do you think this occurred? 4. Rockets are used to launch satellites into space. The size of the rocket needed is increased based on the payload (weight of the cargo). Based on the mass of the lemons, batteries and solar panels, which would be a better choice to supply the largest amount of power with the least amount of weight? Would a combination of any of these elements be beneficial? Explain Overview: Teacher Resources Students will build a simple battery and test its voltage and current using a multi-meter in a simple series circuit. Students will connect batteries in series to measure effects of combining batteries in series. Students will mass the batteries, calculate the power produced by the cells to compare and contrast the efficiency of the benefits of using batteries and solar panels. August 13, 2008 Page 11 of 12

12 Materials: 1 Small DC motor Multi-meter 3 Alligator clips 2 Galvanized nail 2 Copper wires 2 Lemons 2 D cell batteries 2 AA cell batteries 2 small solar panels Permanent marker Masking tape Set-up: Divide students into groups of two to three members. Stations may be used if supplies are limited. Individual ammeters or voltmeters may be used if multi-meters are unavailable. Mark all batteries, panels, and batteries for students. Low voltage LED s may replace the motor. Make sure Current is tested in series! All equipment can be located at your local electronics store, i.e. Radio Shack, except for the lemons. Explore current and voltage by connecting multiple batteries or photovoltaic cells in series. August 13, 2008 Page 12 of 12