Question Video: Recalling the Effect of an Electric Potential Difference on Electrons in a Wire | Nagwa Question Video: Recalling the Effect of an Electric Potential Difference on Electrons in a Wire | Nagwa

Question Video: Recalling the Effect of an Electric Potential Difference on Electrons in a Wire Science • Third Year of Preparatory School

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The picture shows the electrons and atomic nuclei in a section of copper wire. The blue circles represent electrons and the red circles represent atomic nuclei. An electric potential difference is set up between the left-hand end and the right-hand end of the wire. Which of the following statements best describes what will happen in the wire? [A] The electrons will move toward the center of the wire. [B] The electrons will begin to move toward one end of the wire. [C] The electrons will move outside of the wire. [D] Nothing will happen.

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Video Transcript

The picture shows the electrons and atomic nuclei in a section of copper wire. The blue circles represent electrons, and the red circles represent atomic nuclei. An electric potential difference is set up between the left-hand end and the right-hand end of the wire. Which of the following statements best describes what will happen in the wire? (A) The electrons will move toward the center of the wire. (B) The electrons will begin to move toward one end of the wire. (C) The electrons will move outside of the wire. (D) Nothing will happen.

This question is asking about the behavior of electrons in a copper wire when an electric potential difference is present. Let’s recall that a copper wire is conductive. This means that electrons are able to move freely between atoms in a copper wire. Let’s also recall that if an electric potential difference is set up between the two ends of the wire, this results in an electric current in the wire. And now, let’s recall that an electric current is a flow of electric charges in a single direction.

We see then that an electric potential difference across the left- and right-hand ends of the wire will result in the electrons in the wire all moving in a single direction. This means that option (D) must be rejected, as it states that nothing will happen. And we know that something will happen; an electric current will be produced, and the electrons will move in the wire. The other options all say that the electrons will move, but each option describes different electron motion directions. We must determine which option describes the motion of the electrons correctly.

Option (C) states that electrons will move outside of the wire. Recall that since copper is a conductor, electrons are able to move freely between atoms in a copper wire. Now, an electron cannot get outside of the wire by moving between atoms that are in the wire. We must therefore reject option (C).

Option (A) states that electrons will move toward the center of the wire. For electrons to move toward the center of the wire, some electrons must move toward the left, while other electrons must move toward the right. If this happened, the electrons could not all be moving in the same direction. We’ve seen though, that an electric potential difference produces an electric current, which means the electrons are all moving in a single direction. So, we should reject option (A).

The correct answer is option (B). The electrons will begin to move toward one end of the wire when an electric potential difference is set up between the ends of the wire.

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