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13.8: Perform an Activity pg. 567 Key Concepts: 1. Current is the rate of electron flow. 2. Potential difference is a measure of the difference in electric potential energy per unit of charge between two points. Determining the Relationship between Current and Potential Difference Purpose: To determine the relationship between the current and the potential difference. Equipment and Materials - variable DC power supply - voltmeter - graph paper - switch - ammeter - 6 conducting wires - resistor Simulation web site: https://phet.colorado.edu/en/simulation/circuit-construction-kit-dc Procedures: 1. Construct a table to record your observations. 2. Make sure that the power supply is turned off. Record the resistance of the resistor (in ohms) in your table. The resistance value is printed on the resistor, or your teacher will provide you with the rating. (10.0 Ω) 3. Connect the circuit shown in Figure 1 Figure 1 4. Turn the power supply on, and set it to a low setting as instructed by your teacher. Close the switch. Record the potential difference (in volts) and the current (in ammeters) in your table. Then open the switch. 5. Increase the setting on the power supply and close the switch again. Record the potential difference and the current in your table. Then open the switch. 6. Repeat step 5 until you have five sets of data. Observations: Table 1: Series Circuit (one Lamp 10 Ω) Change in Power Voltage (V) Current (A) #1 9.0 V #2 12.0 V #3 15.0 V #4 18.0 V #5 21.0 V Resistance (Ω) Analyze and Evaluate: a) Plot a graph of potential difference (on the y-axis) versus current (on the x-axis) [t/i] b) Draw a line of best fit on your graph. You do not necessarily need to place the line through zero. [t/i] c) Calculate the slope of the line of best fit. [t/i] d) Compare the value of the slope with the resistance value of the resistor. What do you notice? [t/i] e) What is the relationship between current and potential difference? [t/i] f) Compare the relationships between current, potential difference, and resistance. Use a graphic organizer to help you [t/i, com] Apply and Extend: g) Suppose you perform the activity with another resistor placed in series in the circuit. Would you expect to record a graph with a slope that is higher or lower than with one resistor? Why? Design and carry out an activity to test your hypothesis? [t/i, com] Conclusion: