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Difficulty: MediumElectrical Current and Electron Flow

A technician connects a 12-volt direct-current (DC) power supply to a two-way radio circuit. According to electron flow theory, how do charge carriers physically move through the external wiring?

  1. A
    Electrons move from the positive terminal, through the radio, toward the negative terminal.
  2. Electrons move from the negative terminal, through the radio, toward the positive terminal.Answer
  3. C
    Electrons oscillate back and forth in place without any net directional movement through the circuit.
  4. D
    Electromotive force creates static potential across the wire without causing physical particle drift.

Answer

Electrons move from the negative terminal, through the radio, toward the positive terminal.
In solid metallic conductors, electric current is the physical drift of free electrons. Because electrons have a negative charge, they are repelled by the negative terminal of the DC power source and attracted toward the positive terminal through the external circuit.

Step-by-Step Solution

1
Identify the nature of the power source and charge carriers
The circuit is powered by a direct-current (DC) source where charge carriers in metallic conductors are negatively charged electrons.
Understanding the carrier polarity is essential for determining movement under an electric field.
2
Apply electrostatic attraction and repulsion principles
Electrons carry a negative charge and are therefore repelled by the negative battery terminal and attracted toward the positive terminal.
Like charges repel and opposite charges attract.
3
Determine the physical direction in the external path
In the external circuit outside the power supply, electron flow proceeds from the negative terminal through the load to the positive terminal.
Electron flow theory describes the actual physical movement of electrons.

Key Concept

Electron flow theory dictates that in a DC circuit, electrons drift through the external conductor from the negative terminal to the positive terminal.
Estimated Time:35s
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Topics

Electrical Current and Electron Flow

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