Power companies use _________ generators and transformers for cost-effective transmission over long distances.

Power companies primarily use alternating current (AC) generators and transformers for the transmission of electricity over long distances because of the inherent advantages that AC systems provide.

One of the main reasons for this preference is that AC voltage can be transformed to much higher voltages using transformers. High voltage transmission reduces the amount of current flowing through the conductors for the same power level, which minimizes resistive losses (heat) in the wires over long distances. This is crucial for efficient energy distribution, as lower power loss means more energy reaches the end user, resulting in cost savings and improved system reliability.

AC also allows for the use of complex power systems and enables easy conversion between different voltages using transformers—an essential feature for long-distance transmission, where voltage levels need to be adjusted at various points along the line. In contrast, while direct current (DC) can also be used for transmission, particularly in specific applications such as undersea cables, it does not have the same flexibility with transformers or the same efficiency for long-distance transmission under most circumstances.

This makes AC the standard choice for most power companies dealing with widespread transmission networks.