How frequently does alternating current change direction?

The correct choice reflects that alternating current (AC) changes direction 60 times per second, which is a fundamental characteristic of the electrical systems used in North America. This is tied to the standard frequency of AC power supply, which operates at 60 Hz. In other words, an AC waveform completes one full cycle of current direction change (positive and negative) 60 times within one second.

Understanding this concept is essential because the frequency of the AC current affects the design and operation of electrical equipment and systems. Devices and appliances are often designed to operate optimally at this frequency, and deviations can result in inefficiency or even failure.

Other options propose different frequencies, but they do not align with the standard used in most household and commercial electrical systems in North America. Using the correct frequency is critical for safe and efficient operation of electrical devices.