Final answer:
The current that flows back and forth during a pulse in a PC is called alternating current (AC). Alternating current moves in one direction and then reverses periodically, unlike direct current (DC) which flows in a single direction.
Step-by-step explanation:
In a PC, the current that flows back and forth during a pulse is called alternating current (AC). This type of electrical flow is characterized by charges moving in one direction and then reversing to move in the opposite direction at regular intervals. Alternating current is used in many applications, such as in household electricity supplies, because it can be more efficiently transmitted over long distances and easily transformed into different voltages.
Direct current (DC), on the other hand, involves the flow of electric charge in only one direction and is often used for battery-powered devices. AC current in a circuit, as in the case of a fluorescent light bulb, can cause the light to brighten and dim repeatedly as the current goes through zero, which can happen at a high frequency such as 120 Hz. This results in a flicker that is generally too rapid for the human eye to detect.