What is the biggest single advantage of alternating current (AC)?

The biggest single advantage of alternating current (AC) is its ability to be transformed from one voltage to another. This characteristic allows AC to be transmitted efficiently over long distances with minimal losses. By increasing the voltage for transmission, the current can be reduced, which lowers the energy lost as heat in the conductors due to resistance.

Transformers play a crucial role in this process by stepping up or stepping down voltage levels as needed for various applications, making AC versatile for different needs, from high-voltage transmission lines to lower voltages suitable for residential or commercial use. This capability significantly enhances the efficiency and practicality of electrical power distribution systems compared to direct current (DC), which cannot be transformed in the same way and therefore lacks the same efficiency for long-distance transmission.

While easier generation, safety for residential use, and consistent flow direction are considerations in the use of AC, the transformative ability is what makes AC fundamentally advantageous for widespread power distribution.