PHYS 122 Lab 5 Draft Report

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Name(s): Kirsten North Date: 10/05/2023 Ohm’s Law Purpose The objective of this experiment is to determine the connection between the voltage applied to a resistor, the resulting current passing through it, and the resistance of the resistor. To accomplish this, students will employ ammeters and voltmeters for precise DC electrical measurements of both current and voltage. Apparatus - EM 8675 PASCO kit ○ 47 ࠵? resistor,100 ࠵? resistor ○ wires with alligator clips ○ 2 x 1.5 V batteries - Multimeter Procedure 1. Gather the required materials, including a 47Ω resistor, 100Ω resistor, wires with alligator clips, two 1.5 V batteries, and a multimeter. 2. Start by measuring the voltage output from a single battery and record its actual voltage value. 3. Series Connection: Wire two batteries in series with each other. This combination should yield an output voltage approximately twice the nominal voltage of a single battery, which is about 3 V. 4. Use these batteries to vary the voltage applied to the resistor during the experiment. 5. Circuit Setup: Build a simple circuit by connecting the 100Ω resistor to the batteries. 6. Use the ammeter to measure and record the current passing through the 100Ω resistor when connected to one battery. Repeat this for when it's connected to two batteries. 7. Measure and record the voltage across the resistor when it's connected to one battery and again when it's connected to two batteries. Keep in mind that this voltage will be slightly less than the output voltage of the disconnected battery. 8. Repeat the entire experiment using the 47Ω resistor. Data Table 1: Voltage and Current Measurements for 100Ω resistor Number of Batteries Voltage (V) Current (A) 0 0.000 0.000 1 1.499 3.000 2 2.488 4.008 Table 2: Voltage and Current Measurements for 47Ω resistor

Name(s): Kirsten North Date: 10/05/2023 Number of Batteries Voltage (V) Current (A) 0 0.000 0.000 1 1.500 3.100 2 2.510 4.210 Evaluation of Data This chart shows the values of the current versus the voltage for 100 ࠵? with a line of best fit included. -0.5 0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Voltage (V) Current (A) Current (A) vs Voltage (V) For 100Ω

Name(s): Kirsten North Date: 10/05/2023 This chart shows both the values of the 100 ࠵? and 47 ࠵? and both of their trendlines. The blue data points are for 100 ࠵?, and the gray data points are for 47 ࠵?. - Write the equation for the line in the manner that you’ve learned in lab 0, including the units of the slope, and using physics variables instead of y & x. The slope should be a number with units in this equation. The equation for the data points with 100 ࠵? can be written as ࠵? = 0.593࠵? ∗ ࠵? − 0.0563࠵? The equation for the data points with 47 ࠵? can be written as ࠵? = 0.5719࠵? ∗ ࠵? − 0.057࠵? - What does the slope of the line represent? The slope is equal to the resistance of the component in the circuit. It tells you how much the voltage across the resistor changes for a given change in current. A steeper slope indicates higher resistance, meaning that the resistor resists the flow of current more effectively. - Compare the two trend-lines, which has the greater slope? The 100 ࠵? trendline has a greater slope. - Which allows more current, when 3V are applied? When 3V are applied, the resistor with the lower resistance allows more current to flow. This is because according to Ohm's Law, ࠵? = ! " , where I is the current, V is voltage, and R y = 0.5719x - 0.057 y = 0.593x - 0.0563 -0.5 0 0.5 1 1.5 2 2.5 3 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Voltage (V) Current (A) Current (A) vs Voltage (V) For 100Ω and 47Ω

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Name(s): Kirsten North Date: 10/05/2023 is resistance. With 3V, if the resistance is lower, the denominator R is smaller, which results in a larger current I . - Why is resistance the appropriate term: what is being ‘resisted’? Resistance represents what's being "resisted" in an electrical circuit, which is the flow of electric current. It measures how strongly a resistor or other electrical part pushes back against the flow of electrons. Conclusion - Write the general form of the equation of best fit for your lines, and describe this equation in a complete sentence. ࠵? = ࠵?࠵? This equation shows that the voltage across the component (V) is equal to the current (I) flowing through it multiplied by the resistance (R) of that component. - The new term is resistance. What are the units of resistance, and how does this new unit relate to the quantities you’ve measured in this exercise? The unit of resistance is the ohm (Ω). In this lab, we have measured voltage (V) in volts (V) and current (I) in amperes (A). Resistance (R) is calculated as the ratio of voltage to current (R = V/I). The unit of ohms (Ω) tells us how strongly a component opposes the flow of electrons (current) for a given voltage. - If we’d plotted current vs voltage, instead of voltage vs current, we’d find the slope as the conductance. Explain which resistor will have the greater conductance. The resistor with the smaller resistance will have a greater conductance, and the resistor with the larger resistance will have a lower conductance. Since 47Ω is smaller than 100Ω, the 47Ω resistor will have a greater conductance when the current-voltage graph is plotted. Conductance is essentially a measure of how easily current flows through a component, and lower resistance allows for higher conductance.