Electricity & Magnetism: Ohm's Law

Explore the relationship between current and voltage for a simple DC circuit with a resistor in series with a capacitor. Do the same for a light bulb in series with a capacitor. Compare the plot of voltage versus current for the light bulb to the plot for the resistor.

Motion Sensors

Students will discover that the slope of their voltage/current graph is the resistance in the circuit (Ohm's Law). Enlarge graph.

Lab Summary:

Students will use the Voltage/Current Sensor to investigate the relationship between current, voltage, and resistance in a direct current (DC) circuit.

Students will measure voltage and current for a circuit with a resistor in series with a capacitor as the capacitor is discharged through the resistor. They will repeat the measurement with a different resistor. They will examine the slope of a plot of voltage versus current and compare the slope to the resistance of the circuit.

Students will measure the voltage and current for a circuit with a light bulb in series with a capacitor as the capacitor is discharged through the light bulb. They will compare the plot of voltage versus current for the light bulb to the plot for the resistors.

Download free labs:

(student versions)

Computer-based lab (PDF, 554 KB)

Xplorer GLX-based lab (PDF, 592 KB)

Method:

Use a Voltage-Current Sensor to measure the voltage across a resistor and the current through the resistor as the voltage is increased. Examine the graph of voltage versus current and compare the slope of the graph to the resistance of the resistor.

Here's What You Need:

Required for computer-based lab:

(See lab download for Xplorer GLX-based lab requirements, which may differ)

Probeware

Other Materials

Lab Manual:

The computer-based activity is included in Explorations in Physics (PS-2810). The Xplorer GLX-based lab is included in Physics with the Xplorer GLX (PS-2826). Both manuals are complete with Teacher Information pages, student instructions and handouts, and sample data.

For your convenience, we offer bundles which provide the probeware for the activities in the manual. For more, please see:
Computer-based Physics Lab Manual and Bundles
Xplorer GLX-based Physics Lab Manual and Bundles