167 168 lab 6 electricity from magnetism in the

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Unformatted text preview: tement of physics will result in a maximum of 60% of the total points achieved; incorrect grammar or spelling will result in a maximum of 70% of the total points achieved) BONUS POINTS FOR TEAMWORK (as specified by course policy) * An "R" in the points column means to rewrite that section only and return it to your lab instructor within two days of the return of the report to you. 167 168 LAB 6: ELECTRICITY FROM MAGNETISM In the previous problems you explored the magnetic field and its effect on moving charges. You also saw how electric currents could create magnetic fields. This lab will carry that investigation one step further, determining how changing magnetic fields can give rise to electric currents. This is the effect that allows the generation of electricity, which powers the world. The problems in this laboratory will explore different aspects of changing the magnetic flux through a coil of wire to produce an electric current. You will investigate the current produced in a coil of wire by moving the coil, moving the magnet causing the magnetic field, changing the area of the coil perpendicular to the magnetic field, and changing the magnetic field. OBJECTIVES: After successfully completing this laboratory, you should be able to: • Explain what conditions are necessary for a magnetic field to produce an electric current. • Determine the direction of a current induced by a magnetic field. • Use the concept of magnetic flux to determine the electric effects of a changing magnetic field. • Use Faraday's law to determine the magnitude of a potential difference across a wire produced by a change of magnetic flux. PREPARATION: Read Tipler & Mosca: Chapter 28, sections 1,2 & 4. Before coming to lab you should be able to: • Use a DMM to measure current, potential difference, and resistance. • Sketch the magnetic fields from permanent magnets and current carrying coils of wire. • Use vector addition to combine magnetic fields from several sources. • Use the right-hand rule to determine the direction of the magnetic fields from circuit loops and wires. 169 LAB 6: ELECTRICITY FROM MAGNETISM • Use a Hall probe to determine the strength of a magnetic field. • Use the definition of magnetic flux. 170 PROBLEM #1: MAGNETIC INDUCTION One of the great technical problems in modern society is how to generate enough electricity for our growing demand. You work with a team investigating efficiency improvements for electric generators. Before becoming involved with a lot of math and computer simulations, you decide to get a feel for the problem by seeing how many different ways you can generate a potential difference with just a bar magnet and a coil of wire, and how you can influence the size of that potential difference. Instructions: Before lab, read the laboratory in its entirety as well as the required reading in the textbook. In your lab notebook, respond to the warm up questions and derive a specific prediction for the outcome of the lab. During lab, compare your warm up responses and prediction in your group. Then, work through the exploration, measurement, analysis, and conclusion sections in sequence, keeping a record of your findings in your lab notebook. It is often useful to use Excel to perform data analysis, rather than doing it by hand. EQUIPMENT You have a small coil of wire and a bar magnet. You will use a voltage probe with software called VoltageTimeLAB. S N Ammeter Read the section Magnetizing a Bar Magnet in the Equipment appendix if you need to remagnetize your magnets. Read the section VoltageTimeLAB - MEASURING TIME-VARYING VOLTAGES in the Software appendix. If equipment is missing or broken, submit a problem report by sending an email to [email protected] Include the room number and brief description of the problem. PREDICTION Restate the problem. How many different ways can you use the magnetic field of the bar magnet to induce a potential difference across the ends of a coil of wire? Draw a diagram of each procedure that, you predict, will induce a potential difference across the ends of the coil. What do you think will influence the size of the potential difference? Explain how you arrived at your predictions. 171 MAGNETIC INDUCTION – 1302Lab6Prob1 EXPLORATION Plug the voltage probe into the SensorDAQ interface using the required Ch. 1. Attach the clips to the two ends of the coil and start the VoltageTimeLab program. Make sure you read the software appendix if necessary. Using the magnet and the coil, make sure that the apparatus is working properly and that you are getting appropriate potential difference graphs on the screen. From your predictions, how many different motions did members of your group think of to induce a potential difference across the ends of the coil? List them in your journal. Test each method and record the results. Did any method not produce a potential difference? For each method, what factors affect the magnitude and sign of the induced...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.

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