Direction of drift velocity vs direction of current

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    Current Drift Velocity
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Discussion Overview

The discussion centers around the relationship between drift velocity and conventional current in conductive materials, particularly in wires. Participants explore the definitions and directions of these concepts, considering different charge carriers such as electrons and holes.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question whether the direction of drift velocity is the same as that of conventional current, noting a lack of consensus in available resources.
  • One participant explains that conventional current represents the flow of positive charge, while electrons, being negatively charged, flow in the opposite direction.
  • Another participant asserts that the drift velocity of conventional current aligns with the direction of holes, which are considered positive charge carriers.
  • There is a discussion about the definition of holes, with one participant describing them as vacancies left by electrons in a material.
  • Some participants highlight that while the original post refers to wires, electron drift can also occur in vacuum environments, such as in vacuum tubes.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between drift velocity and conventional current, particularly regarding the role of charge carriers. No consensus is reached on the directionality of these concepts.

Contextual Notes

The discussion reveals a dependence on definitions of charge carriers and the contexts in which they are applied, such as in solid conductors versus vacuum environments. There are also unresolved questions about the implications of these definitions on the understanding of drift velocity.

MrBlank
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TL;DR
Is the direction of the drift velocity in a wire the same as the direction of the (conventional) current?
I've done internet searches on this. There doesn't seem to be any agreement. Is the direction of the drift velocity in a wire the same as the (conventional) current?

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Baluncore said:
The diagram is labeled "Drift velocity of electrons". You could just as easily make a diagram labeled "Drift velocity of holes".

Is the conventional drift velocity in the same direction as the conventional current?
 
Conventional current is the flow of positive charge in one direction. Electrons have negative charge, so if they are the mobile species they flow in the oposite direction to the conventional current. It was an unfortunate sign choice.
 
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MrBlank said:
Is the conventional drift velocity in the same direction as the conventional current?
If you are going to use the term "drift velocity", you must specify clearly what charge carrier you are referring to.
The conventional current drift velocity is in the same direction as the conventional current, which is in the same direction as the holes.
 
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What are holes in a current carrying wire?
 
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Meir Achuz said:
What are holes in a current carrying wire?
A hole is the place where an electron was before it moved. Another electron can then drop into that vacant hole.
https://en.wikipedia.org/wiki/Electron_hole
 
I think the OP had electrons in mind ("standard" metal). As for holes, they are a very useful tool to study solid media where electrons some behave strangely but holes aren't empty locations in normal 3D space.
 
The OP specified "wire" but electron drift also occurs in vacuum. Though out of vogue, vacuum tubes demonstrate electron motion without the cumbersome chemical characteristics of copper wire and related metal carriers.

Essentially, electrons 'boil off' the cathode, traverse free space, then collect on the anode. Grids, plates, magnetic fields, RF inputs and electrostatics keep things interesting. Electron bunching and drift play a major role in my namesake klystron design, indeed all TWTs.
 

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