Ontario Grade 9 Science Practice Exam 2026 – Complete Study Resource

Potential difference is a measure of the electrical force that drives a current through a circuit. While joules, amperes, and ohms are all important measurements in electricity, they are not used to directly measure potential difference. Joules measure energy, amperes measure current, and ohms measure resistance, but not potential difference. Therefore, these options are incorrect. The correct unit to measure potential difference is volts, as it is the unit used to express the strength of an electrical potential or intensity of an electric current.