What is a signal that goes from negative to positive called?

The correct answer is AC, which stands for Alternating Current. AC is characterized by the flow of electric charge that periodically reverses direction. This results in a signal that oscillates between negative and positive values over time. In practical applications, AC is commonly used for power supply in households and businesses, as it can be easily transformed to different voltage levels and is efficient for long-distance transmission.

The nature of AC signals allows them to effectively power devices and systems that require a varying voltage. This oscillation provides a continuous flow of electricity that can be utilized efficiently in various electronic applications, distinguishing it clearly from other types of signals and currents.

In contrast, Direct Current (DC) maintains a constant polarity, flowing steadily in one direction. A pulse signal refers to a sudden change in voltage level that occurs over a short time period and returns to a baseline level; while an impulse signal is a type of pulse signal that is typically very brief but has a high amplitude. These characteristics do not align with the concept of a signal that transitions from negative to positive like AC does.