Which of the following statements about average voltage is true in AC circuits?

The average voltage in an alternating current (AC) circuit typically refers to the average value taken over a complete cycle of the waveform. In most common AC waveforms, particularly sinusoidal ones, the average voltage is less than the effective voltage, also known as the root mean square (RMS) voltage.

The effective voltage represents the DC equivalent voltage that would deliver the same power to a load. For a pure sinusoidal wave, the relationship can be understood better with numerical values: the RMS voltage is about 0.707 times the peak voltage, while the average voltage for a sinusoidal waveform is about 0.637 times the peak voltage. Thus, it's a fundamental property that the average voltage in AC circuits is indeed usually less than the effective voltage, making this statement true.

Options mentioning equivalencies to peak voltage or RMS voltage do not accurately reflect how average voltage operates within the context of AC circuits, as average voltage is generally less than both of those values. Meanwhile, average voltage is not measured in AC amperes, as amperes are a unit of current, not voltage.