Final answer:
The average voltage Vavg of the source refers to the average value of the voltage. In AC circuits, the most commonly used average value is the root mean square (RMS) voltage, which is designated as Vrms.
Step-by-step explanation:
The average voltage Vavg of the source refers to the average value of the voltage. In AC circuits, the most commonly used average value is the root mean square (RMS) voltage, which is designated as Vrms. Vrms is calculated using a mathematical process that involves squaring the voltage function, taking the mean, and finding the square root. This value is not zero and is used to represent the average voltage of the source.