Which current flows in one direction?

Which current flows in one direction?

• A. Alternating Current (AC)
• B. Pulsating DC
• C. AC with ripple
• D. Direct Current (DC)

Answer: (D)

Current that flows in one direction means the charge moves steadily toward the same end of the circuit without reversing. This happens when the source has a fixed polarity and the path allows current to go in a single way, which is Direct Current. In Direct Current, the voltage polarity stays the same, so the current maintains a single direction over time. Alternating Current reverses direction periodically as the voltage polarity changes, so it does not flow in just one direction. Pulsating Direct Current does not reverse direction either—it still flows in one direction, but its magnitude rises and falls; however, the standard unidirectional, steady flow described by Direct Current is the clearest fit. AC with ripple also alternates direction, just with fluctuations in magnitude, so it does not meet the criterion of flowing in one direction.

Current that flows in one direction means the charge moves steadily toward the same end of the circuit without reversing. This happens when the source has a fixed polarity and the path allows current to go in a single way, which is Direct Current. In Direct Current, the voltage polarity stays the same, so the current maintains a single direction over time. Alternating Current reverses direction periodically as the voltage polarity changes, so it does not flow in just one direction. Pulsating Direct Current does not reverse direction either—it still flows in one direction, but its magnitude rises and falls; however, the standard unidirectional, steady flow described by Direct Current is the clearest fit. AC with ripple also alternates direction, just with fluctuations in magnitude, so it does not meet the criterion of flowing in one direction.