1202_LabManual.pdf

# Use the dmm to measure the current in the coil try

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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 Equipment 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? A NALYSIS 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. C ONCLUSION 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? 136

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