How is the average voltage over one entire cycle of AC typically expressed?

The average voltage over one entire cycle of alternating current (AC) is commonly expressed as root mean square (RMS) voltage. This is because RMS provides a meaningful way to quantify the effective value of alternating voltage, allowing for an accurate comparison to direct current (DC) voltage.

RMS voltage is derived by taking the square of the instantaneous voltages over a complete cycle, averaging those values, and then taking the square root of that average. This method accounts for the varying nature of AC signals, resulting in a value that reflects the equivalent DC voltage that would produce the same amount of power in a resistive load.

When engineers specify voltage in terms of RMS, it helps in the analysis and application of AC power in circuits and systems, making it a standardized measurement in electrical engineering. While peak voltage represents the maximum voltage achieved in a cycle and effective voltage gives a good measure of average power delivered, the RMS value is specifically designed to represent the effective voltage for power calculations.

Thus, RMS voltage is the most appropriate and accurate expression for defining average voltage over one full cycle in AC systems.