Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Lemon Battery Mini Lesson Batteries use chemical reactions to create an electric current. In 1800 Alessandro Volta made the first battery by layering copper and zinc in a jar of salt water. The chemical reaction created the first steady supply of electricity. The steady supply of electricity from batteries is used to power all sorts of electrical devices such as toys, light bulbs, radios, calculators and cars. Following Volta’s example we can make batteries, too. Materials 6 lemons, oranges, or other fruit 5 bags containing 1 lead with alligator clip, one paper clip, and one penny 1 bag containing same as above plus items below and extra supplies Knife Voltmeter Light emitting diode (LED) that requires low voltage and low current battery Preparation Prepare the lemons for use in the battery by placing the lemons one by one on a flat surface and firmly pushing down on them with one hand while rolling them back and forth. This is to break up the insides of the fruit so the juices can flow more easily. Use a knife to make two small incisions in the middle of each of the lemons. The cuts should be about ½ inch long, deep enough to reach the juicy insides of the fruit, and about ½ inch apart. It is helpful if the slits are above and below one another rather than side to side. What To Do Give each student a lemon. Demonstrate with the remaining lemon(s). In each lemon insert a penny into one of the slits so only a small part of the coin remains on the outside of the lemon. Do the same with a paperclip in the other slit. Line up all of the lemons so that the inserts alternate in order (i.e. penny, paperclip, penny, paperclip, penny . . . ). Have the students use an alligator clip to connect to the penny. Check to be sure all of the clips attach only to the penny! Have each student pass the free end of their lead (wire) to the person on their right. (Direction doesn’t matter, just be consistent). Students should take the free end of the lead just handed to them and connect it to their paperclips You the instructor should not attach the lead handed to you to your paperclip. Instead, explain that you have made a battery and that you will test it with a voltmeter. Be sure the switch is to the left on the voltmeter. Use the snap on your own lead to connect to the – side of the black voltmeter. Use the free alligator lead from the person to your left to connect to the positive side of the voltmeter. The arm should swing to between one and two volts. If it doesn’t move, have each student in turn gently pull out and push back in the paper clip and penny and check that the clips are firmly attached. [If the voltage is very low test each lemon separately using the wires connected to the penny and paperclip in each lemon. Lemons that are not working well can be adjusted by squeezing them to break up more of the tissue inside, moving the penny and the paperclip, or refastening the wires to the penny and the paperclip in slightly different locations. Also, check that the penny and paperclip do not touch each other directly.] Once the lemon battery is working well, as confirmed by the voltmeter, it can be used to power the LED. Gently bend the legs of the LED away from each other. Connect the wire that leads from the paperclip to the side of the LED that is flat and has the shorter leg. Connect the wire from the penny to other leg of the LED. Dim the lights in the classroom and the glow from the LED should be visible. Questions 1. What else might the lemon battery be able to power? 2. What other types of fruits might be used to make batteries? 3. If more lemons were used to make the battery would the amount of electricity it produced be different? Would the voltmeter show a higher, lower, or the same reading? Summary Electricity is the flow of electrons. Electron flow can be produced by some chemical reactions, including this one between zinc from the paperclip, the copper from the penny, and the citric acid in the lemon juice. The chemical reaction takes some positively charged zinc ions from the paperclip, leaving behind an excess of negatively charged electrons. Electrons are much more strongly attracted to copper than zinc, and will move along the wire toward the copper penny. The penny draws positive ions from the lemon juice solution, and then the electrons flow from the negatively charged paperclip to the positively charged penny. This flow of electrons is the electricity produced by the lemon battery. Extension What else can the lemon battery power? Remove the battery from a simple calculator and attach wires to the positive and negative terminals for the battery. Connect the lead from the paperclip to the negative terminal and the lead from the penny to the positive terminal of the calculator. Does the calculator work? Try a few calculations. Sources "How Science Works," Judith Hann, Reader’s Digest, Dorling Kindersley Limited, 1991, p. 151. "Fruit Cell" in "Awesome Experiments in Electricity and Magnetism." Michael DiSpezio, Sterling Publishing Company, 1998, p. 102. ISBN 0-8069-9819-9 © S. Olesik, WOW Project, Ohio State University, 2001.