In electrical terminology, a phase is defined as:

• A. A complete, elapsed cycle as measured from a reference point
• B. The instantaneous voltage at a point
• C. The temperature of a conductor
• D. The number of cycles per second

Answer: (A)

In electrical terms, phase is about where you are in the repeating cycle of a waveform relative to a reference point. Imagine a sine wave and start your clock at a chosen reference, such as the zero-crossing where the wave passes upward. As time progresses, you move through the cycle from 0 degrees up to 360 degrees. Saying a phase equals a complete, elapsed cycle from that reference point captures the idea that phase tracks the progression through one full cycle.

The other options describe something different: instantaneous voltage is the current value of the waveform at an instant, temperature has no relation to the electrical phase, and the number of cycles per second is frequency, not phase.

So the best choice reflects phase as the progression through a full cycle measured from a reference.