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Unformatted text preview: ugh the ring, and when it has? Will the peaks be sharp or rounded? Will
there be many peaks or only one? How will the signal look different from background
noise? Draw on your experiences from problems 1 and 3 in this lab.
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. 182 THE MAGNITUDE OF THE INDUCED POTENTIAL DIFFERENCE – 1302Lab6Prob4
Push the bar magnet through the coil to make sure that the apparatus is working
properly and that you are getting appropriate signal on the screen. How does the graph
compare to your expectations? Make sure you can freeze the screen while showing
your desired data.
Set up the track at an incline so that a rolling cart will go through the center of the coil.
Try different angles to get the most reproducible situation in which you can change the
velocity of the cart over the widest range without damaging the equipment. Be sure to
have someone catch the cart when it reaches the end of the incline.
Securely attach a bar magnet to the cart and let it roll down the track while observing
the potential difference displayed by the computer. Check that the release position
does affect the potential difference graph on the computer. Try different time scales
over which the computer makes the measurement. Are the differences large enough to
Does the orientation of the magnet matter? Try different orientations. Do the magnetic
bumpers in the cart matter? Try a cart without a bar magnet.
Does the display of the potential difference as a function of time on the computer look
as you expected? Be sure you can qualitatively explain the behavior that you see
displayed. You might want to move the magnet by hand to see if your understanding is
Try adding another bar magnet to the cart to increase the magnitude of the induced
potential difference. Does it matter how the second magnet is oriented?
Develop a measurement plan to take the data you need to answer the question. MEASUREMENT
Follow your measurement plan and record the maximum potential difference across the
ends of the coil of wire as a function of the velocity of the magnet through the coil. ANALYSIS
From your data construct a graph of maximum induced potential difference in the coil
as a function of the distance from the coil at which the cart is released.
Add the graph of your prediction to the same plot and compare. You may need to
normalize the graphs. 183 THE MAGNITUDE OF THE INDUCED POTENTIAL DIFFERENCE – 1302Lab6Prob4 CONCLUSION
Did your results agree with your predictions? Explain any differences.
From the computer screen, make a sketch of the shape of the induced potential
difference across the ends of the coil as a function of time for one pass of the magnet.
Label each feature of the graph and indicate where the magnet is in the coil at that time
and why the graph looks like it does at that time. 184 PROBLEM #5: THE GENERATOR
To begin investigating how to improve the efficiency of electric generators, your
supervisor assigns you the task of building a working model of a generator from which
it is easy to take measurements. Your model consists of Helmholtz coils to generate a
well-defined magnetic field and a smaller coil of wire, in between the Helmholtz coils,
to generate the current. The small coil is mounted to a motor so that it spins at a
Before presenting the model to your supervisor you calculate the potential difference
you expect and then take some measurements to make sure that the results correspond
to your understanding of the situation. You will need to determine how the expected
potential difference may depend on time, the rate of small coil rotation, and other
parameters in your setup.
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 28.4. EQUIPMENT
The small coil mounts to the base between the Helmholtz coils, as
shown to the right. The Helmholtz coils are connected to a power
supply. The small coil is labeled with the # turns of wire, and can
be rotated by a motor. DO NOT connect a power supply to the
small coil or you will damage it.
You will have a Hall probe, a DMM, and a meterstick. You will
also have a voltage probe with the VoltageTimeLAB software. s mall coil Helmholz
coils Read the sections The Magnetic Field Sensor (Hall Probe) & The Digital Multimeter in the
Read the sections Volta...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.
- Spring '14