EG10112 Module 4 Independent Design and Demonstration of an Engineering System Initial Report
Submitted to: Dr. Rachel Getman Section 11 Group 2 April 2, 2009
_______________ Arambula, Joseph _______________ Crish, Ashley _______________ Hunter, Charles _______________ Kelly, John _______________ Pan, Yichao
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TEAM MEMBERS The purpose of this project is to work collaboratively as a team to demonstrate a physical property. Each member brings unique skills to the group, as shown in Table 1. Table 1. Team Members with Critical skills and the Corresponding Roles Name John Kelly Yichao Pan Charlie Hunter Ashley Crish Joseph Arambula
Role Coordinator Recorder Quality Assurance Operations Liaison
Critical Skills Programming Drawing graphs Analytical thinking Organization, accounting Communication
PHYSICAL PROPERTY The physical property that will be demonstrated is magnetic induction. A changing magnetic flux in a changing magnetic field can induce a current in a stationary loop wire bounding a surface. For example, the model in Figure 1 has a pair of fixed magnets and a rotating coil.
Figure 1. An AC Generator from Physics for Scientists and Engineers Reference: http://ebooks.bfwpub.com/physse6e/figures/28_22.gif
The voltage generated in the wire is equal to the time rate-of-change of magnetic flux. If there are N turns of wire in a coil, each has an induced voltage that is in series with the others so that the net induced emf is given by the equation
(1)
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where
is the EMF (voltage) generated, N is the number of turns in the coil, B is the magnetic
field, A is the area of the flat surface bounded by the coil, ď ˇ is the angular frequency of rotation and t is the time. The motivation behind this experiment is to demonstrate the linear relationship between the angular frequency of rotation and the voltage induced. From this demonstration, other engineering students can witness the relationship between magnetism and electricity, specifically, how spinning magnets can induce an electric current through a wire. DESCRIPTION OF IDEA The current idea for the demonstration is an electric generator. The simple electric generator which will be built should generate enough electricity to power a small incandescent light bulb or something else which does not require much electricity to be powered. The generator will be made using the Lego model kits, Lego Brick, several magnets, copper wiring, and a light bulb, as shown in Figure 2.
Figure 2. Drawing of Magnetic Generator
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The base of the generator will be made of the Lego parts which will help insure that none of the electricity generated is dissipated elsewhere. At the top of the base there will be an enclosure containing magnets which are free to rotate. The rotation of the magnets will be powered by the Lego Brick using an NQC program. The Lego Brick will have a few similar programs to rotate the magnets, but will vary the velocity which they are rotating. Copper wiring will surround the outside of the enclosure which means it will also surround the magnetic field inside. When the demonstration is running the magnets will rotate. This rotation will cause the magnetic field to change and a voltage appears. The faster the magnetic field changes, the larger the voltage becomes. The changing magnetic fields try to create electric currents in closed circles of wire. The rotating magnets force the electrons in the copper wiring coil to begin flowing. This generation of an electric current through the wiring is called electromagnetic induction. The generator creates enough electricity to power a small light bulb because it does not just have only one circle of wire around it. The copper wiring is going to be wrapped around the enclosed magnets around 200-300 turns. The small voltage from each turn will add together to create a much larger voltage. In the demonstration, the copper wire coil turns are constant. The light bulb connects the ends of the coil together to create the closed circuit. The charges within the copper wire pass into the thin light bulb filament which greatly increases the speed of the charge. Inside the filament, the charge heats the metal filament so hot that it glows. The wires of the generator also become heated, but since the wires are thicker almost all of the heating occurs in the light bulb filament. Once the charge leaves the filament and flows back into the copper wire it slows down again. A multimeter will read the value of the voltage and current created by the generator. The varying rotation speed will cause changes in the voltage and
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different readings in the multimeter and thus conclude the demonstration. A future engineer would measure the principles of magnetic induction and see how one can predict the voltage produced by magnetic induction. They will see how a combination of coiled wire and spinning magnet can produce a current. Our project will explain one way in which electricity can be created using kinetic energy. A future engineer could measure the amount of loops we use, the angular velocity of the spinning magnet and the voltage produced relative to the strength of the magnets. By keeping two of these three variables constant, one could calculate the actual current created using Farad's law of induction. Once the current has been found the amount of electrical energy produced can be calculated. TIME LINE This project involves many phases to be completed throughout the next five weeks. To ensure the efficiency of the project, the timeline in Table 2 will be utilized. Table 2. Time Line Date (2009) March 29
Time 17:30
Event Meeting to cover initial report and presentation, finalize parts list
March 30 April 3 April 3-6 April 9
18:30 15:30 N/A 15:30
April 12 April 16 April 19 April 23 April 25 April 27 April 29
17:30 15:30 17:30 15:30 17:30 12:50 NLT 12:00 N/A
Excursion to Lowes to purchase supplies LC 4: Initial report and presentation First peer evaluation LC5: Parts distribution, obtain parts supplied by learning center, build time Build meeting LC6: Meet with faculty member, build time Final building phase, equation development LC 7: Demonstration Poster construction, final report writing Poster presentation Final report due
April 30-May 3
Second peer evaluation
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