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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
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
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.
- Spring '14