How far from the center of the coil along the axis

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Unformatted text preview: application. Be sure the sensor amplification switch on the Hall probe is set to 6.4mT range. The MagnetLab application requires the probe to be set to the 6.4mT range to work correctly. Does the Hall probe ever read a zero field? Explore the strength of the magnetic field in the plane of the coil. Is the field stronger inside or outside the coil? Where is the field the strongest inside the coil? How far from the center of the coil along the axis can you measure the field? Is it the same on both sides of the coil? How can you tell by your magnetic field reading if you are on the axis? How far from the axis can you move the Hall probe without introducing additional uncertainty in your measurement? Write down a measurement plan. MEASUREMENT Based on your exploration, choose a scale for your graph of magnetic field strength as a function of position that will include all of the points that you will measure. Use the Hall probe to measure the magnitude and direction of the magnetic field as a function of position along the axis of the coil. Measure the field on both sides of the coil. Be sure your Hall Probe is calibrated and has the correct orientation to accurately measure the magnetic field. Use the Hall probe to complete the field map for the coil. Use the DMM to measure the current in the coil. Try measuring the field along the axis at several different currents. If you are not familiar with a DMM, see the suggested appendix. Pay special attention to the connections and settings that are used to measure voltages and currents, and why the DMM should be connected in the circuit differently for voltage and current measurements. Do you know why we should connect them in these ways? Don't forget to measure the diameter of the coil and record the number of turns. What considerations need to be made when measuring the diameter? 146 THE MAGNETIC FIELD OF ONE COIL – 1302Lab5Prob4 ANALYSIS Graph the magnetic field of the coil along its axis as a function of position and compare to the magnetic field of the bar magnet along the comparable axis. The graphical comparison is easier if you normalize the function describing the bar magnet’s magnetic field to that of the coil. You can do this by dividing the largest magnetic field strength of the coil by the largest magnetic field strength of the bar magnet. Use the resulting number to multiply the function representing the bar magnet’s magnetic field strength. You may also need to use the same process on the x-values. You can then put both functions on the same graph. CONCLUSION Is the graph of magnetic field strength as a function of position along the central axis similar to that for a bar magnet? Does the magnetic field map for a current-carrying coil have the same pattern as for a bar magnet? Do you believe that this coil gives a magnetic dipole field? Is this true everywhere? Why or why not? How does the magnetic field strength of a current-carrying coil depend on the current? What measurements justify your statement? 147 THE MAGNETIC FIELD OF ONE COIL – 1302Lab5Prob4 148 PROBLEM #5: DETERMINING THE MAGNETIC FIELD OF A COIL You have a job in a microelectronics laboratory and need to shape a silicon wafer with a precision of a few microns. Your team decides to investigate using an ion beam to do this accurate cutting. You know that an ion is just an atom with some of its electrons stripped off, so you could direct it with a magnetic field. One of the members of your group suggests that a coil of wire can be used to produce a variable magnetic field. You have been assigned to calculate the magnetic field along the axis of the coil as a function of its current, number of turns, radius, and the distance along the axis from the center of the coil. To make sure you are correct, you decide to compare your calculation to measurements. Note: This problem is fundamentally the same as the problem Measuring The Magnetic Field of One Coil, but requires that you derive the expression for the magnetic field produced by a current carrying coil. If you have already acquired data for that problem, no new data is required. 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 27 Section 2 and Example 27-2. EQUIPMENT You have a coil of 200 turns of wire, an 18volt/5amp power supply, a compass, meterstick, digital multimeter (DMM), Hall probe and a computer data acquisition system. You will also have the EMField application. Do not use the Cenco CRT power supply for this problem. DMM P ower S upp ly y x Read the sections The Magnetic Field Sensor (Hall Probe) & The Digital Mul...
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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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