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ASVAB · Electricity Basics

What is the difference between AC and DC electrical current?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

AC (alternating current) periodically reverses direction; DC (direct current) flows in one constant direction

  1. A They are the same
  2. B AC has no voltage
  3. C DC only exists in power lines
  4. D AC (alternating current) periodically reverses direction; DC (direct current) flows in one constant direction

Why this is the answer

AC (ALTERNATING CURRENT) periodically REVERSES direction (flows back and forth); DC (DIRECT CURRENT) flows in ONE constant direction. ASVAB Electronics Information tests current types. AC is used in household wiring and power distribution (it's easy to transform to different voltages for long-distance transmission); DC comes from batteries and is used in electronics (and produced by solar cells). Devices often convert AC to DC (via a rectifier/power adapter). In the US, household AC alternates at 60 Hz. Knowing AC reverses direction while DC is one-directional is commonly tested.
Source: ASVAB Electronics Information — AC vs DC

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About this topic: Electricity Basics

Electricity basics define the quantities everything else depends on: voltage, current, resistance and power, their units, and the difference between AC and DC, conductors and insulators. This is one of 13 Electronics Information questions on electricity basics, each with a full explanation on a single study page.

New to this exam? Our ASVAB exam guide explains the format, scoring, and how to prepare.

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