Lab_Report_6

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California Polytechnic State University, Pomona *

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1101L

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Electrical Engineering

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Jan 9, 2024

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P a g e | 1 ECE 1101L – Lab 6 Potentiometer Name: Leyi Zhou Group: L 09/27/2023

P a g e | 2 Introduction Background Theory: Potentiometer is a variable resistor with 3 terminals, which means we are able to adjust the resistance value of the potentiometer by changing its direction, and we are able to use it to change the voltage of the circuit. We followed the instructions in the lab to make a table of R1, R2 and the total R in the given POT (Potentiometer) in 5 different positions. Objective: In this experiment, we learned the characteristics and how to use the POT, and we took measurements of the values of the resistance for different directions of the POT in a circuit. For part 1 of this experiment, we measured the values of R1, R2 and R for 5 different positions of the knob of potentiometer. For part 2 of this experiment, we chose the input voltage of our circuit as 10V, and we turned the knob of the potentiometer so that the voltage of it, V2, was half of the input voltage which was 5V. After we recorded all data, we made a table of the values of R1, R2 and R for part 1, and another table of the values of V2, R2 and R3 for part 2. By comparing all the data, we would like to verify that the total resistance R of the POT = R1 + R2 for part 1, and R2 and R3 had the same resistance if the voltage of the POT, V2 was 5V for part 2.

P a g e | 3 Lab

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P a g e | 4

P a g e | 5 Data Analysis: For Part 1 of this lab, we turned the knob of the Potentiometer in the circuit, and measured R1, R2 and the total R for 5 different positions of the knob. We recorded the values of R for 5 times, which ranged from 9.689 kOhm to 9.692 kOhm, and by comparing them with the values of R1 + R2, we were able to determine for this Potentiometer, R = R1 + R2. For Part 2 of this lab, we changed the direction of the POT such that the voltage of this potentiometer, V2 was 5V, and we also recorded the value of R2 = 5.051 kOhm and R3 = 5.546 kOhm, with a percentage difference = (5.546 – 5.051) kOhm / 5.051 kOhm * 100% = 9.80%. Since the percentage difference was under 10%, we were able to find out that the values of R2 and R3 were almost the same. Therefore, we were able to verify that if V2 was 5V in this circuit, the values of R2 and R3 should be the same. Conclusion In this experiment, I learned that unlike other types of resistors, the potentiometer is a variable resistor and its characteristics are very useful for building a circuit, in which we are able to turn the knob (the position) of the POT to adjust the resistance value for each terminal, and the total resistance value of the entire potentiometer. Also, I learned that the values of the resistance of two terminals of the potentiometer were equal to the total value of resistance of that potentiometer, R1 + R2 = R, and when the voltage of the potentiometer V2 was 5V, the values of resistance of two terminals, R2 and R3 should be the same. For part 1 of this experiment, the values of R we measured were close to each other, and they all equal to the values of R1 + R2 for each trial. For part 2 of this experiment, while V2 was 5V which was half of the input voltage, the resistances values between 2 terminals of the potentiometer, R2 and R3 were almost the same, which was around 5.05 – 5.5 kOhm. However, there was a small percentage difference between the values of R2 and R3 which was 9.80%, and there were several possible factors causing this percentage difference include the instability of the voltage source, and the instrumental error of the Ohmmeter while measuring the values of R2 and R3.