Lab 3 copy

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School

University of Kentucky *

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213

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Electrical Engineering

Date

Jan 9, 2024

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pdf

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Uploaded by KidField4475

Lab 3: Resistors in Series and Parallel PI: Mason Player DA: Sahil Shah R: Collin Duerler Introduction (DA) This is Lab 3; this experiment focused on resistors in series and parallel. A series is when two more resistors must have the same current; this is called "in series," and we can combine their resistances. Parallel is when two or more resistors must have the same voltage difference; this is called "in parallel" and can combine their resistances. The purpose of this lab was to investigate the relationship between current and voltage and the characteristics of resistors in a series and parallel connection. The DDM (digital multimeter) measures resistance, voltage, and current. The results of this lab were in a series circuit; the first resistor's output current flows into the second resistor's input. The current stays the same for each resistor that was tested. In the parallel circuit, all the resistors lead onto one side of the resistors, they are all connected, and all the leads on the other side are connected. Our findings to this experiment suggested the resistance is the quotient of voltage and current that keeps the current constant. Using Ohm’s Law, we calculated the R ohms = 6667.67 ± 0.0005Ω . The Digital Multimeter (DMM) also measured the resistance across all 4 resistors. We calculated R DMM = 5587 ± 0.5Ω Procedure (R) In this lab, our goal was to build a circuit with a mixture of resistors in series and parallel. To find the resistance of these four resistors, we used three different methods that all found similar answers 1 . One method was to use the galvanometer to find the current of the circuit which was then used to find the resistance using Ohm’s Law. Ohm’s Law is, V=IR and can be rearranged to solve for resistance using voltage and current. Another method was to use bands on the resistors to find resistance. This was done by looking at bands on each resistor and looking at chart based on the color to determine resistance. The last method we used to determine resistance was to use a multimeter to give us a reading of the resistance of the circuit. Each of these ways was to find resistance of individual resistors, but to find the total resistance we use equations that finds resistance of resistors in parallel and series. To find resistance of series we used, 𝑅 ?? = 𝑅 ? + 𝑅 ? and parallel was 𝑅 ?? = 𝑅 ? 𝑅 ? 𝑅 ? +𝑅 ? We then used an equation for effective resistance to find the total resistance of the circuit, 1 R: Q1

𝑅 ?????𝑡𝑖𝑣? = 𝑅 ?? 𝑅 ?? 𝑅 ?? + 𝑅 ?? One large source of systematic uncertainty was likely the 5% tolerance on each of the resistors we used. 2 A (DA) Our Raw Computed data is above showing all the results calculated from the individuals colors and Series and parallels, along with the mixed. In the scatter plot above, the RDMM is depicted for every individual color. The orange dots depict the Rohm along the y-axis as the error bars. Conclusion (PI) 2 R: Q2

 Schematic Drawing of Circuit(PI 2) The resistance for the four resistors was: R a = 1000  50  R b = 1500  75  R c = 2000  100  R c = 3000  150  Using the Standard EIA Color Code Table, the combined resistance of the four resistors was R mixed = 6200  0.005  , we found this using the formula below R mixed = R c + R d R a ∗ R b R a + R b Using Ohm’s Law, we calculated the R ohms = 6667.67 ± 0.0005Ω . The Digital Multimeter (DMM) also measured the resistance across all 4 resistors. We calculated R DMM = 5587 ± 0.5Ω . The scatter plot from the DA shows the resistance calculated from R ohms and R mixed were close in values, but 𝑅 𝐷𝑀𝑀 calculated from the digital multimeter, was slightly less than the other two values. This could be due to an error we made completing this lab, resulting in values that aren’t completely accurate. Although these values may be slightly inaccurate, our group did successfully collect accurate data to support our values for each of the resistors. We compared the resistances from R ohms and R mixed to R DMM , which helped us conclude that the resistance in the mixed circuit was greater than the resistance in the parallel circuit.

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