List the important characteristics for inducing a

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Unformatted text preview: potential difference? Make sure everyone gets a chance to manipulate the magnet and coil and control the computer. Can you discover any methods you didn't think of earlier? What is the largest potential difference you can generate? CONCLUSION How do your results compare with your predictions? Explain any differences, using pictures or qualitative graphs where they are helpful. State clearly the physics involved. List the important characteristics for inducing a potential difference in the coil of wire. Explain how they are related to the magnitude and sign of the induced potential difference. How do you get the largest potential difference? 172 PROBLEM #2: MAGNETIC FLUX You are working on a project to build a more efficient generator. A web search reveals that most existing generators use mechanical means such as steam, water, or airflow to rotate coils of wire in a constant magnetic field. To design the generator, you need to calculate how the potential difference generated depends on the orientation of the coil with respect to the magnetic field. A colleague suggests you use the concept of magnetic flux, which involves both the magnetic field strength and the orientations of the coil and magnetic field. You decide that you need to calculate the magnetic flux through the coil as a function of the angle between the coil and the magnetic field. To help you qualitatively check your calculation, you use a computer simulation program. You then quantitatively test your calculation by modeling the situation in the laboratory. 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. Read: Tipler & Mosca Chapter 28.1. EQUIPMENT Diagram of Flux Simulation screen to right. Fr ame Read the sections The Magnetic Field Sensor (Hall Probe) & The Digital Multimeter in the Equipment appendix. Read the sections Flux Simulator and Measuring Constant Magnetic Field in the Software appendix. Magnet i c Fi el d Di r ect i on Fr ame' s Ar ea Vect or t hr ough Fr ame Fr ame Ey e 173 Ey e' s v i ew of f l ux passi ng t hr ough f r ame MAGNETIC FLUX – 1302Lab6Prob2 To make the measurement, a magnetic field sensor (Hall probe) is placed midway between two Helmholtz coils as shown to the right. The sensor can be rotated and the angle of rotation measured. The sensor measures the amount of magnetic field perpendicular to the area of the Hall effect chip (white dot). The MagnetLab application will be used to with a Hall probe. Sensor Helmholz coils WARNING: You will be working with equipment that generates large electric currents. Improper use can cause painful burns. To avoid danger, the power should be turned OFF and you should WAIT at least one minute before any wires are disconnected from or connected to the power supply. If equipment is missing or broken, submit a problem report by sending an email to labhelp@physics.umn.edu. Include the room number and brief description of the problem. WARM UP 1. Draw the coil of wire at an angle to a magnetic field. 2. Draw and label a vector that you can use to keep track of the direction of the coil. The most convenient vector is one perpendicular to the plane of the coil, the area vector. Label the angle between the area vector and the magnetic field. 3. The magnetic flux for a constant magnetic field is the component of the magnetic field perpendicular to the plane of the coil times the area of the coil. Write an equation for the magnetic flux through the coil as a function of the strength of the magnetic field and the angle between the area vector and the magnetic field direction. For what angle is this expression a maximum? Minimum? PREDICTION Calculate the magnetic flux through an area (the frame of the simulation or the Hall effect transducer chip for the measurement) as a function of the angle that the area makes with the direction of the magnetic field. Use this expression to graph the magnetic flux versus angle. In the simulation program, under what conditions will the “eye” “see” the most intense blue color? The most intense red color? Will there ever be no color, or white? As the 174 MAGNETIC FLUX – 1302Lab6Prob2 Frame is slowly rotated, will the transitions in intensity be sudden, or gradual? Is the change in intensity linear or something else? EXPLORATION Open the Flux Simluator movie. Use the control bar with slider, which advances through the movie, to control the rotation of the frame. Try it. Slider As you rotate the frame, observe both the angle that the frame's area vector makes wit...
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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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