In AC power supplies, is there typically a negative and positive line?

In AC (Alternating Current) power systems, there is typically no fixed polarity as seen in DC (Direct Current) systems. In AC, the voltage periodically reverses direction, which means that the current alternates back and forth between positive and negative values over time. This alternating nature is what distinguishes AC from DC, where one line is consistently positive and the other negative.

Therefore, it's accurate to say that AC does not have a fixed positive and negative line, as the current alternates between these states without being assigned a permanent designation of positive or negative. This characteristic of AC is fundamental to its operation and is why it's commonly used for power distribution in homes and businesses, as it allows for efficient transmission over long distances.