Direction of drift velocity vs direction of current

  • Context: High School 
  • Thread starter Thread starter MrBlank
  • Start date Start date
  • Tags Tags
    Current Drift Velocity
Click For Summary
SUMMARY

The direction of drift velocity in a wire is opposite to the direction of conventional current when electrons are the charge carriers, as electrons carry a negative charge. Conventional current, defined as the flow of positive charge, aligns with the drift velocity of holes, which represent the absence of electrons. It is essential to specify the charge carrier when discussing drift velocity, as this determines the direction of flow. In vacuum tubes, electrons can traverse free space, demonstrating drift velocity independent of solid-state materials.

PREREQUISITES
  • Understanding of conventional current and charge carriers
  • Familiarity with drift velocity concepts
  • Knowledge of electron and hole dynamics in semiconductors
  • Basic principles of vacuum tube operation
NEXT STEPS
  • Research the role of holes in semiconductor physics
  • Study the principles of electron drift in vacuum tubes
  • Learn about the differences between conventional current and electron flow
  • Explore the applications of drift velocity in klystron and TWT designs
USEFUL FOR

Physics students, electrical engineers, and anyone interested in understanding the behavior of charge carriers in conductive materials and vacuum systems.

MrBlank
Messages
17
Reaction score
2
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?

[AI Chatbot reference deleted by the Mentors]
 
Last edited by a moderator:
Physics news on Phys.org
Baluncore said:
See the diagram.
https://en.wikipedia.org/wiki/Drift_velocity
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.
 
Reply
  • Like
Likes   Reactions: Klystron, Vanadium 50 and Meir Achuz
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.
 
Reply
  • Like
Likes   Reactions: nasu, Klystron and Dale
What are holes in a current carrying wire?
 
Reply
  • Like
Likes   Reactions: davenn and Ibix
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.
 

Similar threads

High School Applying the Gauss (1835) formula for force between 2 parallel DC currents
  • · Replies 6 ·
Replies
6
Views
625
Undergrad Does current decrease inside a wire or does it increase it's velocity?
  • · Replies 8 ·
Replies
8
Views
2K
High School Deriving Current from Drift Velocity Basics
  • · Replies 2 ·
Replies
2
Views
7K
Undergrad How relative is the magnetic field of a current carrying conductor?
  • · Replies 4 ·
Replies
4
Views
1K
Graduate Charge distribution in a resistor with a current
  • · Replies 4 ·
Replies
4
Views
17K
High School Found a circuit where current is zero across an ohmic device (dV>0)
  • · Replies 11 ·
Replies
11
Views
1K
High School The historical war of currents in Mains Power Distribution: AC vs DC
  • · Replies 7 ·
Replies
7
Views
2K
Confused about direction of electric field
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad Understanding dissipation of energy in a resistor through the Drude model
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Dynamics of Lorentz force on a current carrying wire
  • · Replies 2 ·
Replies
2
Views
2K