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Unformatted text preview: rodes. The voltage should read ∼10V. If it is not 10V, check the
output of your power supply and the connections to the electrodes.
• Hold one probe to the electrode connected to the negative of the power supply and use the other
probe to move to various points on the conductive sheet. You should see the voltage increase as you
move closer to the other electrode.
• Hold one probe to the electrode connected to the negative of the power supply and touch the other
one to the ground on the power supply. This should read zero volts, since they are electrically the
Measure the potential difference between the two electrodes and record this on your worksheet. Hold
the "COM" probe to the negative electrode and the "V" probe to the positive electrode. Then reverse the
position of the two probes. Label the voltage of each electrode on your conductive sheet, using the white
wax pencil. What do you notice about these two measurements?
Because there is no potential difference between the output port of the power supply and the electrode
it is connected to, it is easier to connect one input of the voltmeter directly to the power supply instead
of holding both probes. Disconnect the probe in the "COM" terminal and replace it with a banana cable
(remove the alligator clip, if it is attached). Connect this directly to the negative output of the power supply.
Now, the voltmeter is measuring the potential difference between the ground and the probe connected to
the "V" input.
Next we will map a few equipotential lines. Move the point probe around the paper until you ﬁnd a
5 V reading. Mark this point with a white wax pencil. Find another location that is also 5 V and mark it.
Continue marking 5 V points that are 1 to 2 cm apart until you reach the edges of the paper. Sketch line
through all points to indicate the equipotential line. Make sure that the actual measured points are visible;
you may need to make your dots larger to be seen against the line. Label this equipotential line.
Mark two more equipotential lines (3 V and 7 V, 4 V and 6 V, etc.) in this same way.
Equation 1 relates the potential to the electric ﬁeld with a dot product. This indicates that electric ﬁeld
lines cross equipotential lines at right angles. (Why does it indicate that? Think about the operation of the
dot product.) Using this knowledge, sketch two electric ﬁeld lines, complete with their direction, on your
Now we will look at the angular dependence of the dipole potential. Switch both leads on the multimeter back to the point probes. Center the angle template directly between the two electrodes. The hash
marks on the conductive sheet will help you orient the template. The indicated holes are 6 cm apart, at 0◦ ,
30◦ , 60◦ , and 90◦ relative to the axis of the dipole. Keeping the "COM" lead closer to the 0 V electrode,
measure the potential for each of these angles and record them on your worksheet. Make a quick graph of
the potential as a function of the angle. What relationship does it appear to have?
Make sure to write your names on the conductive sheet. You will turn it in with your worksheet. 9 5 Experiment: EKG
Disclaimer: The EKG in this experiment is not a medical diagnosis. If for any reason whatsoever you do not want to take your EKG trace, please ﬁnd a lab partner who is
willing to be the "patient". If needed, have your GSI help to arrange lab partners so that there is a patient
in each pair. Figure 5:...
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This document was uploaded on 02/15/2014.
- Spring '14