RC Circuits
Variant i Dynamics first
Developed by Peter Shaffer (creator) and Rand Harrington (co-creator)
Students examine qualitatively the behavior of capacitors in an RC circuit. Some incorrect ideas about current in an RC circuit and about grounding of capacitors are addressed.
Topics Electricity and magnetism / Electric circuits: models, capacitance, and circuits
Materials
Materials by the UW team
- Equipment List
- Instructor’s Guide
- Sample Pre-test
- Sample Exam Questions
Tutorial details
The tutorial provides students with hands-on experience with RC circuits. It starts with a single bulb and single capacitor circuit. Students make predictions about bulb brightness, construct the circuit, make observations, and compare their results with their predictions. Based on their observations, they infer how the current and voltage for various elements change depend on time.
Students extend their understanding by considering circuits with two bulbs in series and then two bulbs in parallel. They come to recognize that the final charge on the capacitor is the same in both cases although the initial currents differ. They then examine circuits with two capacitors.
The tendency to treat a bulb that lies between two capacitors as electrically unconnected is addressed.
For instruction tips, login or register as a verified educator to see the Instructor Guide.
Prerequisites
Students should have previously been introduced to RC circuits in class. They should also have completed both tutorials on dc circuits.
Equipment
Special Instructions
Each group should be given one 0.5-F capacitor and one 1–Farad capacitor
Groups should also be given ample connecting wire,with alligator clips
List
- D-cell
- voltmeters (5-volt range)
- white board or large sheet of paper with markers
- bulbs (#14) in sockets
- batteries
- battery holders
- capacitors (see comments on equipment)
- switches (single pole-single throw)
Coming Soon! We hope to release the discussion section on each tutorial by the end of July 2024.
