Electron Flow in Short-Circuited Battery: What to Expect?

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Discussion Overview

The discussion centers around the speed of electron flow in a short-circuited battery connected by a copper wire. Participants explore concepts related to electric current, drift velocity, and the behavior of electrons in conductive materials, touching on both theoretical and practical aspects of electricity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the speed of electron flow in a circuit with a shorted battery and copper wire.
  • Another participant provides a link to a Wikipedia article discussing electric current and drift speed.
  • A participant explains that while individual electrons move slowly (e.g., 0.024 cm/sec in a specific scenario), the overall effect is akin to pushing on a pipe full of putty, where the end moves even if the start does not.
  • There is a question raised about whether the speed of electron flow is constant or varies with factors such as volume, electric field (E), or resistance (R).
  • A formula for electric current is presented, relating current (I), charged particle density (n), cross-sectional area (A), drift velocity (v), and charge (Q), leading to a rearrangement that expresses drift velocity in terms of these variables.
  • One participant expresses gratitude for clarifying their long-held questions about electron speed, referencing a past claim from an electronics instructor that electrons move at the speed of light, which they questioned due to mass considerations.

Areas of Agreement / Disagreement

The discussion includes multiple viewpoints regarding the speed of electron flow and its dependence on various factors. There is no consensus on whether the speed is constant or varies under different conditions.

Contextual Notes

Participants reference specific values and concepts without resolving the implications of mass on electron speed or the conditions under which drift velocity may change. The discussion does not clarify the assumptions behind the provided formula or the specific context of the short-circuited battery scenario.

Who May Find This Useful

This discussion may be of interest to individuals studying electricity, electronics, or those curious about the behavior of electrons in conductive materials.

nshamblin
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What is the speed of electron flow in an eletric curcuit? A battery (cell) with a copper wire shorted across the positive and negative posts. What will the electron flow be through the copper wire?
 
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Each individual electron moves very slowly for example in a copper wire of radius 1 mm carrying a steady current of 10 Amps, the drift velocity is only about 0.024 cm/sec.

However because there are electrons throughout the whole length of the copper wire, its a bit like pushing on the end of a pipe full of putty, the putty at the opposite end starts to move even though your end hasn't moved very far.
 
does the speed change? or is it constant? for instance does the speed of I depend on its volume which would in turn be dependent on E or R ?
 
[itex]I = nAvQ[/itex]

Where,

I = electric current
n= charged particles per unit volume
A= cross sectional area of conductor
v= drift velocity
Q= charge of each particle

so therefore

[itex]v = \frac{I}{nAQ}[/itex]
 
Thank you for your help. I've been imersed in labor these past 40 years having to set aside some of the questions I've had since childhood. I thank you for clearing this one up. My electronics instructor years ago said the electrons in a cucuit moved at the speed of light, which I always questioned, because of mass issues, Now I know. thanks again.
 
nshamblin said:
Thank you for your help. I've been imersed in labor these past 40 years having to set aside some of the questions I've had since childhood. I thank you for clearing this one up. My electronics instructor years ago said the electrons in a cucuit moved at the speed of light, which I always questioned, because of mass issues, Now I know. thanks again.


http://www.jimloy.com/physics/electric.htm

This article should explain it a bit better than I did.
 
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