Which statement correctly describes alternating current?

Which statement correctly describes alternating current?

• A. The direction of current reverses periodically
• B. The current flows in only one direction
• C. Voltage is always zero
• D. The current never changes magnitude

Answer: (A)

Alternating current means the flow of electric charge reverses direction at regular intervals. In AC power, the voltage and current rise and fall with time, usually in a smooth wave, so the current switches direction every half cycle. On a 60 Hz line, that reversal happens 120 times per second, which is why the current is described as alternating. The other statements don’t fit: one-way flow is characteristic of direct current, not alternating; voltage isn’t always zero—it's just zero at instants as it oscillates; and the instantaneous magnitude of the current does change with the waveform, even though its effective (RMS) value may stay constant over time.

Alternating current means the flow of electric charge reverses direction at regular intervals. In AC power, the voltage and current rise and fall with time, usually in a smooth wave, so the current switches direction every half cycle. On a 60 Hz line, that reversal happens 120 times per second, which is why the current is described as alternating. The other statements don’t fit: one-way flow is characteristic of direct current, not alternating; voltage isn’t always zero—it's just zero at instants as it oscillates; and the instantaneous magnitude of the current does change with the waveform, even though its effective (RMS) value may stay constant over time.