phase angle

In physics, a phase angle describes the state of a periodic motion, such as vibrations or waves, relative to a reference point in time or position. It represents the fraction of a complete cycle that has passed since the last reference point.1

For instance, in simple harmonic motion, the position can be described by an equation involving amplitude, angular speed, time, and a phase angle. This angle, often represented by Greek letters like omega ((\omega)) and epsilon ((\varepsilon)), helps define the motion's progression.1

When comparing two periodic motions, they are "in phase" if their corresponding points reach maximum or minimum displacements simultaneously. If they are offset, their phase angles differ, indicating they are "out of phase". This concept is crucial in alternating-current technology, where phase differences between voltage and current are measured.1