What is the RMS voltage at a common household electrical power outlet?

The RMS (Root Mean Square) voltage at a common household electrical power outlet in the United States is typically recognized as 120 volts alternating current (AC), which is a standard for residential electricity supply. While 120 V AC is the nominal voltage used for household circuits, the actual voltage can fluctuate slightly due to various factors such as load and delivery conditions.

The RMS concept is crucial in understanding AC systems, as it provides a measure of the effective voltage that would deliver the same power as a corresponding DC voltage. This is particularly important in household appliances that are designed to operate on standard household voltage.

Regarding the options provided, while the answer indicated is 117 V AC, which some calculations and measurements may reflect as an average operational voltage, it is common practice to round this value to 120 V for simplicity and consistency in electrical standards.

Thus, the option denoting 117 V AC can be considered correct in certain contexts reflecting real-world measurements, although it is less common than referring to the standard of 120 V AC. Hence, while recognizing variability is important, the more widely accepted nominal value for household outlets is still 120 V AC.