LAB 3

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School

Texas A&M University *

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Course

217

Subject

Electrical Engineering

Date

Dec 6, 2023

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pdf

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Uploaded by maye0618

LAB 1: USE OF DATA ACQUISITION SYSTEMS TO MEASURE VOLTAGE Rebecca Mathew, Marielva Salas, and Kyle Ford Texas A&M University College Station, TX 77843, US. Abstract This report covers the collection of the Voltage across different wires using the Data Acquisition Unit (DAQ). The experiment aimed to determine the composition of three different wires by analyzing their resistance and resistivity characteristics. The team conducted a series of measurements and analyses using the principles of Ohm's law and the relationship between resistance, resistivity, length, and cross-sectional area. The first part of the experiment involved creating a plot of voltage drop across a segment of a single wire with varying point lengths. In the second part, the team established the Ohmic behavior of each wire by plotting the voltage drop across the entire wire against different current values. The lab results and analyses helped the students better understand the relationship between resistance, resistivity, and material composition, providing valuable insights into the fundamental properties of electrical conductors. Keywords: Voltage, Data Acquisition Unit (DAQ), Uncertainty, Length, Current, Resistance, Resistivity, Conductors 1. Introduction This lab focused on identifying the composition of three wires with varying diameters but the same length. Before conducting the experiment, wire diameters and lengths were measured using calipers and meter sticks. The experiment was divided into two parts. In the first part, voltage measurements were taken by connecting a lead connector to a single wire while maintaining a constant current of 0.1 A. The data was collected using a Python script interfacing with a Data Acquisition (DAQ) system. The experiment aimed to establish a relationship between applied current and voltage for each wire. The data revealed a linear relationship between voltage and current, adhering to Ohm's Law. The slopes of these linear relationships represented the resistance values for each wire. In addition to resistance measurements, the diameter and length of the wires were measured using calipers and meter sticks. These measurements are fundamental in calculating the resistivity of the wires. The resulting data, along with resistance values, were used to assess the composition of the wires. ( l /A) Equation 1 𝑅 = ρ Relationship between resistance and resistivity. Equation 2 σ = ∑(𝑎 𝑖 −µ) 2 𝑁 Where is the standard deviation, is the initial or single value of the data set, is the mean or the average of the data σ 𝑎 µ set, is the total value of the data respectively. 𝑁 Equation 3 𝑢 = σ 𝑁 Where is the uncertainty, is the standard deviation, is the total value of the data respectively. 𝑢 σ 𝑁 Equation 4 𝑉 = 𝐼𝑅

Current between two points is directly proportional to the voltage across those two points. Equation 5 𝐴 = π( 𝑑 2 ) 2 Cross Sectional Area of the wire. 2. Experimental Procedure For this lab, there were three different wires of different diameters, but the same length, stretched across a board. Before conducting the experiment, a thorough measurement of the wires using calipers was taken to determine the diameter, and a measurement of the length of each wires were taken. The lab experiment was broken into two different parts. The first part of the lab required a lead connector with a metal hook attached to a single wire so the voltage could be measured. The power supply was placed at a current of 0.1 A. A python script was used to collect data from the DAQ. For this experiment, the independent variable was the length of the wire segment that was measured and was calculated in millimeters. The length was changed using the metal hook and the current stayed constant. The current was the dependent variable. This process was repeated ten times and the data points were recorded and displayed as seen in Figure 1 in the Results and Analysis section. The second portion of the lab required all three wires. A single lead connected was attached to a wire, in this case Wire 1 so the voltage could be measured. The power supply that was used to supply the current began at 0.01 A and increased 0.01 A until it reached 0.1 A, which was ten measurements. A similar python script was used to calculate this portion of the lab, however the independent variable was not the length, but the amps used. This was repeated for Wire 2 and Wire 3. The data points were recorded and displayed as seen in Figures 2-4. 3. Results and Analysis Figure 1: A single wire lot of a voltage vs length Figure 2: Resistance of Wire 1

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