Lab 1 Electric Field and Electric Potential PDF

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Lab report for Experiment 1: Electric Field and Electric Potential...

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Experiment 1 Electric Field and Electric Potential PHY2049L Section 011

Purpose: The main purpose of this experiment was to chart electric equipotential line and electric field lines for various two-dimensional charge configurations. Theory: The theory behind this experiment was Coulomb’s Law of determining the magnitude of electrostatic force between two point charges into practice. The equation for Coulomb’s Law

F=k

|Qq| r

2

, where k is Coulomb’s constant, Q and q are point charges, and r is the distance

between these charges, allows us to find the magnitude of force. The magnitude of the force can then be used to find the magnitude of the electric field using a test charge (q) with the equation

E=

F . Electric field is a vector meaning it has both magnitude and direction. To find the q

vector quantity of electric field, the equation for finding the magnitude of electric field can be

→

modified by multiplying by

r . In order to map electric field lines it is important to r

understand that electric field lines point away from positive point charges, but toward negative point charges. Electric potential is defined as the potential energy per unit charge, but this scalar value can only be measured as a difference in potential energy between two points. The change in potential energy is equal to the amount of work done by the electric force to move a charge between two points. Method: To test this theory, we used three different sheets of conductive paper with conductive ink electrodes and a voltage probe to map various electric fields. First, we used the voltage probe to test 25 different points on a parallel-plates capacitor. We found that each line parallel to the +10 volts had similar values making them the equipotential lines. Then, we found that each time we measured points on a line that was perpendicular to the +10 volts, the amount of volts decreased as we moved away from the +10 volt charge. These were the electric field lines. Next, we mapped the electric field of a point charge with guard rings using the same method. We found that points that were an equal distance from the point charge, creating halos around it, had similar values. These circular lines were the equipotential lines. Then we found that the further we moved from the point charge, the voltage was decreasing. These were the electric field lines. Lastly, we mapped the electric field around a two point charge configuration using the same

method. We found there to be an electric field around both charges with an equipotential line in between them. Conclusion: My lab partner and I were able to successfully map the electric field lines and electric potential lines for each of the three point charge configurations. In the first measurement, I was able to use the voltage values I found using the probe to find the magnitude of electric field, but there were some discrepancies in my data. My values for the electric field within the parallel-plates capacitor should have all been nearly equal, but instead they ranged from 104.70171.60. Also, in the third measurement, I found that measurements taken at equal distances around each of the point charges were extremely similar. From my understanding of a two-point charge configuration, the equipotential lines should have been more in an ellipse shape with one vertical equipotential line in between the two charges. These discrepancies may have happened due to my misuse of equipment such as not placing the probe exactly perpendicular to each test point....