Lab 4 - Ohm's Law - Completed

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School

Arizona State University *

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Course

112

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Electrical Engineering

Date

Apr 3, 2024

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docx

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Uploaded by CountCrabMaster2055

Sydney Hveem PHY 112 Section 12531 2/12/2024 Lab 4 – Ohm’s Law Lab Purpose While a battery is connected to a circuit, the voltage difference across the battery terminal causes and electric field to form in the current. The charge in the field then moves. We measure this movement of charge using current. Voltage can cause the charge in the circuit to move. Resistors are used to hinder the movement of charge. In this lab, we measure the relationship between voltage and current through a resistor using wired batteries in a series. Materials  Multimeter  5 batteries (1.5 V)  Battery holders  Insulated wires with alligator clips  1 resistor Procedures 1) Using one battery and one resistor, create an unbroken series circuit loop. 2) Connect the black voltmeter wire to the slot marked COM, the red slot and turn the dial to DCV 20.

3) Measure the voltage across the resistor by placing the black voltmeter lead on the side of the resistor connected to the negative end of the battery and the red voltmeter lead on the positive end of the batter. 4) Disconnect one of the wires attached to the resistor and insert the ammeter. Plug the red voltmeter wire into the unfused slot (10 ADC). Turn the dial to DCA 200 m. 5) Measure the current. 6) Repeat steps 3 through 5 adding another battery to the circuit until all five batteries are in the circuit. Photographs

Data Number of Batteries Voltage (V) Current (A) 1 1.4 0.7 2 2.86 1.4 3 4.15 2.1 4 5.3 2.7 5 6.81 3.2 Graphs & Calculations 0.5 1 1.5 2 2.5 3 3.5 0 1 2 3 4 5 6 7 8 f(x) = 2.09 x − 0.13 R² = 0.99 Current vs Voltage Current (A) Voltage (V) Resistance Equation: R = slope R = (6.81 V – 1.4 V)/(3.2 A - 0.7 A) R = 2.164 Ω Voltage Equation: V = IR V = (0.7 A)( 2.164 Ω) V = 1.4 V

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Current Equation: I = Q/t Power Equation: P = IV = V 2 /R P = (0.7 A)(1.4 V) P = 0.98 W Results Using the graph, we can analyze the relationship between voltage and current. The graph shows that as the value of voltage increases, the current also increases. This can be seen by the linear trendline on the graph. Conclusion The purpose of this lab was to measure the relationship between voltage and current through a resistor using wired batteries in a series. This can be done by creating a circuit using insulated wires, batteries and a resistor. When connected, the electrical pressure provided by the battery moves the charge through the wire. Increasing the voltage in the form of adding more batteries, increases the current. When adding a resistor to the current, we are able to resist the current going through the wires. Per the data, we can see that as the voltage of the batteries increased, the current flowing through the circuit also increased. One battery showed a voltage of 1.4 V with a current of 0.7 A. When adding a second battery, the voltage and current increased to 2.86 V and 1.4 A respectively. This shows the direct relationship between voltage and current. This can also be observed in the graph as it has a positive slope of 2.0939. The slope of the graph is also tells us the value of the resistance, which is 2.0939 Ω.

Analysis Questions 1) How would you expect your results to change if the resistor in your circuit had a larger resistance value? Be specific. If the resistor in the circuit had a higher resistance value, the current within the circuit will decrease. This is due to the inverse relationship between current and resistance. 2) What effect would using a 12V car battery have on the operation of your circuit? (Do not try this.) What would happen to the current? What would happen to the resistance? Be specific and include appropriate calculations to support your answers. Due to the voltage increasing to 12V, we would see the current also increase. For example, if the resistance is 15 Ω: I = 20 V/15 Ω I = 1.33 A The resistance would remain the same unless the resistance value was changed. References OpenStax. (2012, June 21). 18.1 Static Electricity and Charge: Conservation of Charge - College Physics | OpenStax . Openstax.org. https://openstax.org/books/college-physics/pages/18-1-static- electricity-and-charge-conservation-of-charge