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Unformatted text preview: ccomplished by entering values into the legend of the graph.
Click on the upper or lower legend value and enter a new value, then hit enter. If you cannot
locate your data, you can select both "AutoScale Y-axis" and "AutoScale X-Axis" to let the
program find the data for you. You can then adjust your axis scales to give you a convenient
graph for analysis. Be careful, the AutoScale option will often set the scales in such a way
that small fluctuations in the data are magnified into huge fluctuations.
Deciding which equation best fits your data is the most important part of using this analysis
program. While the actual mechanics of choosing the equation and parameter is similar to
what you did for your predictions, fitting data is somewhat more complicated.
By looking at the behavior of the data on the graph, determine the best possible function to
describe this data. After you have decided on the appropriate equation, you need to
determine the constants of this equation so that it best fits the data. Although this can be
done by trial and error, it is much more efficient to think of how the behavior of the equation
you have chosen depends on each parameter. Calculus can be a great help here. This can be a
time-consuming task, so be patient.
Now you need to estimate the uncertainty in your fit by deciding the range of other lines that
could also fit your data. This method of estimating your uncertainty is described in Appendix
D. Slightly changing the values for each constant in turn will allow you to do this quickly.
After you have computed your uncertainties, return to your best-fit line and use it as your fit
by selecting Accept Fit in the Command Panel.
Importing / Exporting Data
After you have selected Analyze Data, it is possible to save your data to the computer's hard
drive. This feature can come in handy if you need to analyze your data at a later date or if
you want to re-analyze your data after you have printed it out.
To save your data, simply select Export Data and follow the instructions in the windows.
Your file should be saved in the LabData folder. To retrieve this file, restart MagnetLab from
the desktop and select Import Data.
223 APPENDIX: SOFTWARE Last Words
These directions are not meant to be exhaustive. You will discover more features as you
analyze more data. Be sure to record these features in your lab journal. 224 APPENDIX: SOFTWARE FLUX SIMULATOR
A computer movie called FluxSimulator shows the magnetic flux through a rectangular coil
of wire (called a frame in the program). The frame is rotated in a uniform magnetic field
changing the magnetic flux passing through it. The screen of this simulation is shown below.
The magnetic flux is visualized by a “magic eye” that is always perpendicular to the crosssectional area of the frame (as shown below). The amount of flux "seen" is indicated by the
use of color intensity as the frame rotates. Blue indicates positive flux while red indicates
Fr ame Magnet i c
Fi el d
Di r ect i on Fr ame' s
t hr ough
Fr ame Fr ame Ey e' s v i ew of f l ux
passi ng t hr ough f r ame Ey e Picture of FluxSimulator Screen
Use the control bar with the slider, as shown below, to control the rotation of the frame. Slider
As you rotate the frame, observe both the angle the frame's area vector makes with the
magnetic field and the color seen by the eye. 225 APPENDIX: SOFTWARE VoltageTimeLAB - MEASURING TIME-VARYING VOLTAGES
This software package, written in LabVIEW™, allows you to measure and record potential
differences as a function of time. The software and voltage interface act much like an
After logging into the computer, execute the application by double clicking the
“VoltageTimeLab” icon located in the PhysLab folder on the desktop.
Before you start using the program, you should take a
moment to identify several key elements. The two most
important of these are the Command Panel, shown to the
right, and the Guide Box, shown below. The Guide Box will give you directions and tasks to perform. It will also tell you when to
select a command in the Command Panel.
You can also print and/or quit from the Command Panel or abort your analysis and try
The primary data output you get is by generating pdf files of your results, so be careful not
to quit without printing pdf files or exporting your data.
Since the application to measure time-varying voltage is a slight modification of the
application to measure magnetic field, you are already familiar with how to use much of it.
The basic difference between the TimeVoltageLab and the MagnetLab applications is an
additional display that is much like an oscilloscope. The potential difference versus time
display is shown on the next page. The DAQ (Data Acquisition) control buttons are located
directly above this display. The “DAQ START” and “DAQ STOP” buttons do as they
suggest, stop and start data streaming from the probe to the voltage versu...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.
- Spring '14