What is the frequency of AC electricity in the United States?

In the United States, the standard frequency for alternating current (AC) electricity is 60 hertz. This means that the electrical current changes direction 60 times per second. This frequency is consistent across most electrical appliances and systems in the U.S., ensuring uniformity for household and industrial use.

The choice of 60 hertz as a standard frequency was largely settled upon in the early 20th century due to its balance of efficiency and performance characteristics, which align well with most electrical motors and transmission systems.

In contrast, frequencies such as 50 hertz are commonly used in many other countries, but they are not the standard in the U.S. The other frequency options provided — 70 hertz and 75 hertz — are not standard for electricity supply and thus are not applicable in this context.