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Difficulty: HardDirect Current (DC) vs. Alternating Current (AC)

An electrical current whose magnitude periodically fluctuates over time without ever reversing its polarity or direction of electron flow is classified as an alternating current (AC).

Answer: Answer

Answer

False
The statement is false because the defining characteristic of alternating current (AC) is a periodic reversal in the direction of current flow and voltage polarity. Current that varies in magnitude while remaining strictly unidirectional is pulsating direct current (DC).

Step-by-Step Solution

1
Analyze the fundamental definition of alternating current (AC).
Alternating current requires that electrons periodically change direction, moving back and forth across a zero reference axis.
AC is defined by periodic reversal of polarity and current direction, not merely changing magnitude.
2
Analyze the characteristics of direct current (DC) and its variations.
Direct current is any current that flows continuously in a single direction; when its amplitude varies over time without crossing zero to reverse direction, it is termed pulsating DC.
Unidirectional current flow remains DC regardless of whether the magnitude is constant or time-varying.
3
Evaluate the statement based on electrical classification principles.
The statement incorrectly classifies a unidirectional pulsating current as alternating current.
Because polarity never reverses, the current is DC, making the statement false.

Key Concept

Classification of DC vs. AC based on polarity reversal versus magnitude variation
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Topics

Direct Current (DC) vs. Alternating Current (AC)

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