Electric fields PDF

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Lab Report for electric fields with Margie Abdelzarek...

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Electric Fields Experiment Allison Hodgins and Danielle Kerksick PHYS 222, Section 007 Lab Instructor: Olugbenga Olunloyo Lab Performed on January 17, 2019 Lab Submitted on January 24, 2019

Abstract An electric field is defined as a space in which if a small positive test charge is placed, there will be a force exerted on the test charge (1). The magnitude of such electric field strength is given by the ratio of the force exerted on the test charge (F) divided by the magnitude of the charge (q). In this experiment, electric field strength was measured using a Cenco Overbeck apparatus in which the electric potential was found using a digital voltmeter. The shape of the electrode configuration was sketched out on a piece of paper and placed on the plate with the corresponding conducting electrodes. The electric potential at values 1.0-9.0V was found using the voltmeter in order to establish the equipotential lines. Using the equipotential lines, the electric field lines were plotted perpendicularly and used to determine the electric field strength at particular points along the graph. The electric field strength was found by moving slightly to the left and right of the desired point and dividing the difference in electric potential by the difference in distance between the two points. In completing the experiment using two different electrode configurations, it was found that electric field strength is greater in between the electrodes where there is a higher density of equipotential lines. Results From the first electrode configuration (figure 1), it was found that moving the probe to the left led to a decrease in the measured voltage, while moving to the right resulted in an increase in the voltage. This corresponds to the selection of the left electrode as the zero point, as the ground side of the voltmeter was attached to this electrode. Upon mapping out the electric potential points at each voltage, it was found that the points along each line were equivalent and followed a curved pattern around each individual electrode. The highest density of equipotential lines was found between the two plates, corresponding to the increased electric field strength between the two electrodes. Additionally, while at points A and C the electric field strength was respectively 40 V/m and 50 V/m, at point B the electric field strength was almost three times larger at 150 V/m (figure 1). This appropriately corresponds to the positioning of the parallel plates as point B was placed on the electrode, while points A and C were outside of the two plates. As expected, this indicates that the electric field strength is greater between the parallel plates due to the stronger magnitude of force closer to the source of the charge. At point B the density of the equipotential lines was also greater, further indicating the strength of the electric field. The same principles were mirrored using another electrode as demonstrated in figure 2; however, the pattern of equipotential lines differed due to the orientation of the electrode configuration. Conclusions Overall, our results were consistent with the principles regarding electric field strength. The voltage was found to be constant along each corresponding equipotential line and the strength of the electric field was found to be greater between the two parallel plates. Although the results corresponded to the expected relationship between electric potential and electric field strength, better results could be obtained by minimalizing the amount of human error in the experiment. The plates could be traced more precisely on the graph paper to better depict the exact placement of electrodes underneath the apparatus. Additionally, the potential points and equipotential lines could have been mapped out on a computer system or with more

precision in an attempt to resemble that of the actual electric field. The voltmeter was set to record to the nearest 0.1 V which may have also contributed to the slight error in the mapping out of the equipotential lines and the resulting calculation of the electric field strength values. Despite the appropriate demonstration of electric field principles, replicating this experiment or using a computer system to further minimalize error may lead to further insight and more precise results. References 1 Parks, James E. Contemporary Introductory Physics Experiments, 2nd Edition, Hayden-McNeil Publishing: Plymouth 2014....