What is the main AC power frequency used today?

What is the main AC power frequency used today?

• A. 60 Hz
• B. 50 Hz
• C. 400 Hz
• D. 120 Hz

Answer: (A)

This question tests understanding of the standard frequency used for AC power in electrical grids. Most power systems operate at either 50 Hz or 60 Hz, and 60 Hz is the main frequency in North America and many parts of the world today. This has become the dominant standard because it fits well with the design of generators, transformers, and motors, and historical choices in those regions solidified a common operating frequency. In other regions, 50 Hz is common, but that doesn’t override the fact that 60 Hz is the prevailing mains frequency where it dominates. A much higher frequency like 400 Hz is used in specialized applications, such as aircraft power, to save weight, but it’s not used for general electrical distribution. And 120 Hz isn’t a standard supply frequency; you might see it as the ripple frequency after rectifying 60 Hz AC, but it isn’t the nominal utility frequency.

This question tests understanding of the standard frequency used for AC power in electrical grids. Most power systems operate at either 50 Hz or 60 Hz, and 60 Hz is the main frequency in North America and many parts of the world today. This has become the dominant standard because it fits well with the design of generators, transformers, and motors, and historical choices in those regions solidified a common operating frequency.

In other regions, 50 Hz is common, but that doesn’t override the fact that 60 Hz is the prevailing mains frequency where it dominates. A much higher frequency like 400 Hz is used in specialized applications, such as aircraft power, to save weight, but it’s not used for general electrical distribution. And 120 Hz isn’t a standard supply frequency; you might see it as the ripple frequency after rectifying 60 Hz AC, but it isn’t the nominal utility frequency.