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

A standard portable flashlight is powered by two alkaline dry cell batteries connected in series. What type of electrical current flows through the flashlight bulb when it is turned on?

  1. A
    Alternating current (AC), because current periodically reverses its direction of flow through the filament
  2. Direct current (DC), because electric charge flows continuously in a single, constant directionAnswer
  3. C
    Direct current (DC), because electric current alternates between positive and negative polarities at 60 Hz
  4. D
    Alternating current (AC), because voltage and current represent identical physical quantities in battery circuits

Answer

Direct current (DC), because electric charge flows continuously in a single, constant direction
Batteries produce direct current (DC) because their chemical reactions establish fixed positive and negative terminals, causing electrical charge to flow continuously in a single direction through the closed circuit.

Step-by-Step Solution

1
Identify the power source and its characteristic electrical output
Alkaline dry cells are electrochemical batteries, which produce a steady electromotive force with fixed positive and negative terminals.
Determining the power source type indicates whether the electrical output is unidirectional (DC) or oscillating (AC).
2
Classify the resulting current flow in the closed circuit
Since the battery polarity remains constant, electrons move continuously in one direction through the circuit, which is the definition of direct current (DC).
Direct current is defined by unidirectional charge flow, whereas alternating current regularly reverses direction.

Key Concept

Direct Current (DC) vs. Alternating Current (AC)
Estimated Time:30s
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Topics

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

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