pdf - Discover Sensors

Activity for
Framework Physics 10
To investigate the relationship between current (I),
potential difference (V) and resistance (R) in a simple
circuit using a resistor
This activity relates to OP49 and OP50 of the Junior Certificate Science Syllabus.
Vernier LabPro interface or LabQuest, Laptop, Current Probe, Voltage Probe, Logger Pro, a variable d.c.
power supply, a 10 ohm resistor, and a filament light bulb.
Connect the Current Probe to Channel 1 and the Voltage Probe to Channel 2 of LabPro.
Open the file “25 Ohms Law” in the Physics with Computers/Vernier folder. A graph showing
axes labeled of potential vs. current will be displayed. The LabQuest/laptop displays the potential
difference and current readings.
With the power supply turned off, connect the power supply, 10 ohm resistor, wires, and clips as
shown in the diagram above.
Click ZERO. A dialog box will appear. Click OK to zero both sensors. This sets the zero for both
probes with no current flowing and with no voltage applied.
Make sure the power supply is set to 0 V. Click COLLECT to begin data collection. Monitor the
voltage and current. When the readings are stable click KEEP.
Increase the voltage on the power supply to approximately 0.5 V. When the readings are stable
click KEEP.
Continue to Increase the voltage by about 0.5 V. When the readings are stable click KEEP. Repeat
this process until you reach a voltage of about 5.0 V.
Click STOP.
Activity for Framework Physics 10
The straight line graph through the origin shows that current is proportional to voltage.
The resistance can be found by dividing the potential difference by the appropriate current for
each set of readings and finding an average.
The resistance can also be found by finding the slope of the graph.
Replace the resistor in the circuit with a filament light bulb. Repeat the steps outlined above
increasing the voltage up to 5.0 V again. Comment on the shape of the graph for the filament
light bulb. Why is it different to the graph obtained for the 10 ohm resistor?