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: