Basic Electricity Practice Exam 2026 – Comprehensive Test Prep Guide

Resistance is measured in ohms. An ohm is defined as the resistance between two points of a conductor when a constant potential difference of one volt, applied to these points, produces a current of one ampere, with no electromotive force within the conductor. This relationship is V = I R, so R = V / I. The symbol for the ohm is the Greek letter omega (Ω). The other units listed are not resistance: the Farad is a unit of capacitance, the Henry is a unit of inductance, and the Siemens is a unit of conductance (the reciprocal of resistance).