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Electricity and Magnetism, Part 1 Rationale: According to the California State Science Content Standards, electricity and magnetism are important concepts for 4th grade students. Disclaimer: Some of the procedures for the activities contained in the lessons have been adapted from various resources listed throughout the module. Part 1A: Electric Current introduces ideas of electric current from the microscopic and macroscopic points of view Activity Summary: Introduction Parts of the atom Simple series circuit Microscopic view of circuit Conductors and insulators Conductivity test Experimental conclusions Special materials Part 1 Worksheet Item 1 Part 1 Worksheet Item 2 Part 1 Worksheet Item 3 Part 1 Worksheet Items 4 and 5 Part 1 Worksheet Item 6 Part 1 Worksheet Items 6 and 7 Part 1B: Static Electricity introduces idea of static electricity Activity Summary: Electroscope Charging balloon Balloon/string experiment Balloon/electroscope experiment Review File Summary: E&M_1_doc E&M_1_teachers E&M_1_wksht E&M_1_wksht_key Page 1 Electricity and Magnetism, Part 1 P Part 2: Magnetism introductory explorations with magnetism Activity Summary: Preliminary observations with magnets Introduction of magnetic poles, field lines, and force Magnetic field line visualization Test for magnetism Permeability test Magnetic domains Magnetize an object Problem: how to determine the N end of a magnet Part 2 Worksheet Item 1 Part 2 Worksheet Item 2 Part 2 Worksheet Item 3 Part 2 Worksheet Item 4 File Summary: E&M_doc_2 E&M_2_teachers E&M_2_wksht E&M_2_wksht_key Part 3: Connecting Electricity and Magnetism begins to connect electricity and magnetism Activity Summary: Determine N pole of a magnet Observe magnetic force caused by current Use current induced magnetic force to do work Make an electromagnet Observe current induced magnetic force directionality Review Part 3 Worksheet Item 1 Part 3 Worksheet Item 2 Part 3 Worksheet Item 3 Part 3 Worksheet Item 4 Part 3 Worksheet Item 5 File Summary: E&M_3_doc E&M_3_teachers E&M_3_wksht E&M_3_wksht_key Part 4: Electricity, Magnetism, and Work applications of electricity and magnetism Activity Summary: Observe current induction by moving magnetic field Investigate parameters for changing induced current Complimentary behavior – speaker experiment Build motor Generate electricity File Summary: E&M_4_doc E&M_4_teachers E&M_4_wksht E&M_4_wksht_key Page 2 Part 4 Worksheet Item 1 Part 4 Worksheet Item 2 Part 4 Worksheet Item 3 Part 4 Worksheet Item 4 Electricity and Magnetism, Part 1 Part 1A: Electric Current Objectives: After participating in the program Electricity and Magnetism, Part 1A, students will be able to: assemble a simple circuit using insulated wires, battery, small light bulb, and bulb holder explain that electrons traveling through a completed circuit constitute an electric current recognize that electrons travel readily in some materials and do not travel in others test materials and classify them as conductors or insulators list several uses for conducting and insulating materials Vocabulary: circuit - a complete path over which current may flow open circuit - an electrical circuit that is broken and thus carries no current closed circuit - an electrical circuit that is complete and can carry a current electron - an elementary particle found in all atoms (not in the nucleus) which carries a negative charge proton - an elementary particle found in the nucleus of all atoms which carries a positive charge equal to the negative charge of an electron neutron - an elementary particle found in the nucleus of all atoms which carries no electrical charge conductor - a material through which electricity can readily flow insulator - a material through which electricity cannot readily flow Lesson Plan: Materials: For each group: 3 sets of insulated wires (with alligator clips) 6 V battery light bulb and holder bag of test materials (glass, magnet, washer, marble, Al foil, eraser, nail, rubber band, penny, screen, sponge, wood, plastic, pencil lead, etc.) bag of special materials (ITO coated glass, diode, LED, conductive polymer) For each student: worksheet Time: activity 1: activity 2: activity 3: activity 4: activity 5: activity 6: activity 7: activity 8: 5 minutes 5 minutes 10 minutes 5 minutes 10 minutes 5 minutes 5 minutes 5 minutes Page 3 Electricity and Magnetism, Part 1 Activities: 1. (5 minutes) Have students sketch on their worksheets, two items they used today that run on electricity. Briefly take survey of the students to see how many different items they listed. 2. (5 minutes) Ask the students to identify the parts of the atom and the charges of the various particles on their worksheets. If they have not yet studied the atom, you may want to skip this or simply show them the parts of the atom. 3. (10 minutes) Have students work in groups of 3 or 4, depending on how the room is set up. Hand out boxes containing the bulbs, batteries, wires, and the bag of test materials. Ask students to make the bulb light. There are several ways to make this circuit so have them use two wires, the battery and a bulb in its holder. Ask students to draw on their worksheets the circuit they made. After the students have drawn their circuit, get them to help you draw it on the blackboard for discussion. Go over this circuit and make sure they see that it is like a circle. What happens if one of the wires is disconnected? (The circuit is opened and the bulb no longer lights. This is called an open circuit.) Have them help you trace the path of electrons in the closed circuit. 4. (5 minutes) Move on to what is happening inside the wires. How are the electrons moving? Ask students to draw on the worksheet how electrons would be moving with respect to the atoms inside the wire. (The atoms would be stationary and the electrons would be moving down the wire in one direction or the other.) Now consider that the circuit was opened somehow. Draw the electrons in the wire now . (Electrons would be moving around each atom, but would not travel down the wire.) 5. (10 minutes) Introduce the ideas of conductors and insulators. (In a conductor, electrons are free to move. In a completed circuit, electrons can move around just like in the wire in #4 of the worksheet. Current can flow in a conductor. In an insulator, electrons are tightly bound to the nucleus of each atom. They cannot leave their atoms to flow as a current. Even in a completed circuit, the electrons in an insulator will behave like those in the wire in #5 of the worksheet. Current does not flow in an insulator.) Ask the students to sort the materials from their bags into two piles, one for conductors and one for insulators. Page 4 Electricity and Magnetism, Part 1 Have students fill out the chart (#6) in the worksheet with their predictions as they go. 6. (5 minutes) After giving students some time to sort the test materials, ask them to brainstorm about how to test for conductivity in their materials. Steer the discussion towards the method using the battery, two test leads (insulated wires with alligator clips at each end), and a test object inserted between the leads. If some students have another equally good idea of how to do this, allow them to use their own method. Have students sketch their test circuit in the worksheet. Then have students test the materials to see if they properly sorted them. 7. (5 minutes) Go over the results of the conductivity test and ask students to draw any conclusions (e.g., metal objects conduct electricity). Ask the students to propose uses for the two classes of materials. (e.g.: Wires in an electrical cord would be made from a conducting material; electrical cords have an insulating material around them so we don’t get shocked.) 8. (5 minutes) Hand out the bag of special materials. Have students guess whether each item will conduct electricity or not. Have students test the materials. They will need some guidance, especially for the diode and LED. Ask students which materials surprised them and why. Explain what each item is and that it has special properties that make it behave differently than other similar materials. (The diode and LED (light emitting diode) conduct electricity in only one direction. The LED also gives off light of a specific color when it is in the conducting mode. The ITO coated glass conducts electricity because it has a transparent electrode on one side. The conductive polymer conducts electricity because of its special chemical structure.) Part 1B: Static Electricity Objectives: After participating in the program Electricity and Magnetism, Part 1B, students will be able to: relate static electricity to the parts of the atom express the difference between static electricity and electric current explain that electrons may be removed from an atom and transferred to another object, leaving that object charged describe how a discharge or spark is created when electrons jump from one object to another to re-establish charge neutrality recognize that like charges repel recognize that opposite charges attract name several types of static electricity Page 5 Electricity and Magnetism, Part 1 Vocabulary: electroscope - an instrument for detecting very small charges of electricity static electricity - stationary electrical charges, as those resulting from friction Lesson Plan: Materials: For each group: aluminum foil – one 6” x 6” piece aluminum foil – two ½” x 3 ½ “ strips (length may vary depending on cup size) clear plastic cup (or other plastic cups with a view window cut) small paper clip tape For each student: balloon piece of wool cloth (approximately 12” x 12”) string worksheet Teacher/Volunteer Preparation: 1. Electroscope construction preparation: Cut the aluminum foil pieces (two ½ “ x 3 ½” strips and one 6” x 6” piece per group). The length of the strips may vary depending on the cups used. When hung on the paper clip, the two strips should not touch the table. To make it easier for students to insert the paper clips, pre-punch holes in the bottoms of the plastic cups. A large safety pin tip will work well here. If the cups are translucent, cut out a “window” in one side of the cup so that the hanging strips may be clearly seen. Leave enough of the cup so that it can support itself on a table top. Time: activity 1: activity 2: activity 3: activity 4: activity 5: 10 minutes 10 minutes 5 minutes 5 minutes 10 minutes Activities: 1. (10 minutes) Each group should make an electroscope1,13 to demonstrate that like charges repel. Refer to Figure E&M_1_1 as the electroscope is constructed. Fold out the inner loop of the paper clip and straighten it. Hang the two aluminum foil strips (½ “ x 3 ½”) on the hook still left in the paper clip. Push the straightened end of the paper clip through the hole from inside the cup. When the cup is placed on a table bottom-side up, the two strips should hang beneath the cup without touching the table. Make sure the strips hang straight and are fairly close to one another. Page 6 Electricity and Magnetism, Part 1 Secure the paper clip to the cup with tape. This works best when taping on the outside of the cup where the straight part of the paper clip comes through. Wad up the square piece of aluminum foil in a ball and press it onto the top of the paper clip. Do not wad the foil up too tightly before pressing it onto the paper clip. Students have now built an electroscope. Put this aside for a later experiment. 2. (10 minutes) Give a balloon to each student and ask them to blow it up. Have the students rub a piece of wool on the balloon several times and try to stick it to the wall or their shirt, etc. Let them play with this a bit to see what else the charged balloon will do. After a few minutes, ask the students to stop and describe what they experienced. (Students should report things such as being able to stick the balloon to something, making their hair stand up, hearing sparks, etc.) Does anyone know what causes these things to happen? (static electricity) Ask the students to think of other examples of static electricity. (walking across a carpet and touching a metal object, getting out of a car that has cloth seats, pulling two socks apart right out of the dryer, lightning, spark plugs, etc.) 3. (5 minutes) Now give each student a string and ask them to tie it to their balloon. Work in pairs for this. Have the two students in each pair charge their balloon and hold it by the end of the string. By holding the balloons by the strings, ask students to try to bring the two balloons together (you can also tape the two strings together in a doorway with the two balloons hanging at the same level). What do students observe? (Students should report that the two balloons do not want to be near each other; that the two balloons push each other away repel each other.) What is happening? Can anyone explain what happened to the balloon when you rubbed it with the wool cloth? (When the balloon was rubbed with the wool cloth, electrons were removed from the wool by friction and were transferred to the balloon.) What charge does the balloon now carry? (The electrons cannot easily get off the balloon, so the balloon is charged negatively.) How does this help the balloon to stick to the wall? (An uncharged object attracts a charged object. When the negatively charged balloon comes close the wall, the part of the wall nearest to the balloon becomes positively charged – electrons in the wall just move over a bit. Then the negative balloon can stick to the positive part of the wall. Oppositely charged objects are attracted to each other.) Why did the two negatively charged balloons push each other away? (Two negatively charged balloons repel each other. Similarly charged objects repel each other.) 4. (5 minutes) Page 7 Electricity and Magnetism, Part 1 Charge up the balloon and bring it near the aluminum foil ball of the electroscope13. As the balloon approaches the ball, the two leaves hanging below should start to move apart. If the ball is touched, the strips will jump apart. Observe the strips as the balloon is moved towards and away from the ball. (As long as the balloon still retains some charge, the strips should come back towards one another when the balloon is moved away. Sometimes the strips will be permanently deformed by the moving apart so that the electroscope will not work again until the strips are restraightened and made to hang close together. Also, if the balloon touches the electroscope, some charge will be transferred. In that case, when the balloon is moved away, the strips will stay far apart. You can briefly touch the Al ball with your finger to remove excess charge from the electroscope and the strips will fall back together.) What happened? (As the negatively charged balloon is brought near the electroscope, electrons in the ball will travel down the paper clip and crowd onto the foil leaves. The Al strips now have a net negative charge. They will repel each other and move apart. As the balloon is moved away, the electrons flow back to the ball from the strips and the neutral foil leaves can now come back to their original position. If the balloon touches the ball of the electroscope, electrons will jump suddenly from the balloon onto the electroscope. The resulting negative charge on the foil leaves will cause them to jump apart as well. A net negative charge can be left on the electroscope. As mentioned above, the extra electrons may be removed by touching the ball with your finger.) 5. (10 minutes) Go over things learned. (Objects can be charged by friction. When this happens, electrons are removed from one object and are collected on another object (protons do not move). Similarly charged objects repel each other; oppositely charged objects attract one another. When a charged object is brought near a neutral object or an oppositely charged object, electrons can jump from the neutral object to the positive object, or from the negative object to the neutral object, or from the negative object to the positive object in order to equalize the charges. This movement of charge takes place instantaneously and is called static electricity. Static electricity discharges can do work (lighting up neon glow tube, setting a tree on fire during lightning strike, etc.).) References and Extension Ideas: The following resources were used in developing this lesson plan. Some of the activities were adapted from these sources. Many ideas for extension activities can be found in them as well. 1. The Thomas Edison Book of Easy and Incredible Experiments, Thomas Alva Edison Foundation, John Wiley & Sons, Inc., New York, 1988. 2. www.beakman.com 3. Foss Magnetism and Electricity Module Page 8 Electricity and Magnetism, Part 1 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. www.freeweb.pdq.net/headstrong/mag.htm www.freeweb.pdq.net/headstrong/mag2.htm www.pausd.palo-alto.ca.us/k6science/electric/e_tips.html www.edtech.kennesaw.edu/web/electric.html Exploratorium Science Snackbook or www.exploratorium.edu/snacks/ www.pbs.org/ktca/newtons/12/electric.html www.pbs.org/wgbh/nova/teachersguide/lightning/lightning_sp1.html www.pbs.org/wgbh/nova/specialfx/fxguide/fxmshtr2.html www.pbs.org/saf/4_class/45_pguides/pguide_605/4565_image.html www.pgs.org/saf/4_class/45_pguides/pguide_604/4564_shark.html www.pgs.org/saf/4_class/45_pguides/pguide_602/4542_storm.html www.chss.montclair.edu/~pererat/pertel.html www.chss.montclair.edu/~peretat/perbuild.html www.chss.montclair.edu/~pererat/perwirls.html The Science Teacher, October 1999, “Electromagnetic/Mechanical Resonator”, pp. 56-58. Page 9 Electricity and Magnetism, Part 1 E&M_1_1. Illustration of electroscope construction. a) Fold out inner loop of paper clip: b) Hang aluminum foil strips on hook: c) Push paper clip through hole in cup: d) Tape paper clip in place: e) Press aluminum foil onto top of paper clip (optional view window shown): Page 10