Though electrons are constantly in motion within metals, but there is no current until a...

Question:

Though electrons are constantly in motion within metals, but there is no current until a potential difference is established across it. Explain why.

Electric Current in a Conductor:

When a potential difference is applied across the ends of the conductor, an electric current is established in the conductor, with a net flow of electrons through a cross section of the conductor.

Answer and Explanation:

In a metallic conductor, electric current is established only by applying the potential difference across it, which is explained as below:

  • Although the free electrons in a conductor are in constant zig-zag motion, there is no net flow of electrons through a cross section in the absence of external potential difference.
  • As soon as a potential difference is applied across the conductor, an electric field causes a net drift of free electrons in direction opposite to that of the electric field.
  • As a result, a net flow of electrons is established through a cross section of the conductor, which constitutes an electric current.

Learn more about this topic:

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What is Electric Current? - Definition, Unit & Types

from CLEP Natural Sciences: Study Guide & Test Prep

Chapter 6 / Lesson 7
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