CENCO® AP Physics Lab 2.09: Internal Resistance of a Cell and Kirchhoff’s Rules

Determine the internal resistance of a battery, and find an unknown resistor in a complex circuit.

Introducing the new CENCO AP Physics lab series!

Ideal for AP Physics 1 and 2, AP Physics C, IB DP Physics, and advanced/honors physics courses, each of the 35 experiments is aligned with the revised College Board AP curriculum. These innovative labs go way beyond traditional exercises, turning real-world scenarios into true guided-inquiry investigations. Students are given a goal, but the investigation is driven by their ideas. As they draw conclusions, students report their results using the Claim-Evidence-Reasoning model. The teacher guides and student manuals are authored and reviewed by AP Physics teachers with decades of combined experience, so you can trust the setups to be successful in your classroom. All labs come complete with instructions and materials for one lab group of 2 to 4 students. For your convenience, labs are packaged to allow you to purchase only what is required for each experiment.

In part 1 of this combined lab, students perform an experiment using a potentiometer to measure the current and voltage of a simple circuit when various resistances are applied. By graphing their results, they can determine the internal resistance of the battery, as well as make sense of the attributes of the best-fit line. In part 2, students must design their own experiment to determine an unknown resistance, with the caveat that they use Kirchoff’s laws to support their claims.