What is the term used to describe the average effective AC voltage or current?

The term used to describe the average effective AC voltage or current is the root mean square (RMS) value. The RMS value is particularly significant in electrical engineering as it represents the equivalent direct current (DC) value that would deliver the same power to a load. When alternating current (AC) flows through a resistive load, the RMS value indicates how much work that current can do, effectively allowing for comparisons between AC and DC systems.

The RMS calculation involves squaring the instantaneous values of the AC waveform, averaging those squares, and then taking the square root of that average, which provides a measure that can be directly used in power calculations. This makes the RMS value critical for applications involving AC systems.

In contrast, mean value refers to the average of the waveform over one complete cycle, which does not account for the power factor effectively in AC systems. Peak value represents the maximum instantaneous voltage or current within a waveform but doesn't provide a practical measure for real power delivery. Instantaneous value simply refers to the voltage or current at a specific moment in time, which is not a comprehensive measure for AC power calculations.

Therefore, RMS value is the most appropriate term for describing the average effective voltage or current in an AC circuit.