Investigating the Relationship Between Current and Terminal Potential Difference to Determine the EMF and Internal Resistance of a 9V Alkaline Battery

This investigation explores how current affects the terminal potential difference of a 9V alkaline battery to determine its electromotive force (EMF) and internal resistance.

Using a rheostat and digital multimeters, the student collected data across eight resistance intervals. The results demonstrated a strong negative linear correlation (R² = 0.996), yielding an internal resistance of 2.1 ± 0.5 Ω and an EMF of 8.62 ± 0.55V.

The exemplar is distinguished by its rigorous error analysis, utilizing the half-range method and line of best/worst fit to propagate uncertainties. It provides a sophisticated evaluation of experimental limitations, including battery polarization and the mathematical non-linearity of rheostat-controlled current.