Velocity of electrons in a wire

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SUMMARY

The discussion centers on the drift speed of electrons in a wire and its relationship to electric current. When a voltage is applied, electrons move in the direction of the voltage, resulting in a drift speed that is typically very slow, around 1/10000 of a second. Despite this slow drift speed, a high current flow can be achieved due to the vast number of free electrons present in a wire, approximately 8.5 x 10^28 electrons per cubic meter. This concept is illustrated effectively through a toy demonstration that parallels the behavior of electrons in a wire.

PREREQUISITES
  • Understanding of basic electrical concepts, including voltage and current.
  • Familiarity with electron behavior in conductive materials.
  • Knowledge of drift velocity and its significance in electrical engineering.
  • Basic grasp of the relationship between charge, current, and electron flow.
NEXT STEPS
  • Research the principles of electric current and drift velocity in conductors.
  • Explore the concept of free electrons in different materials and their impact on conductivity.
  • Learn about the mathematical relationship between current, charge, and drift speed.
  • Investigate practical demonstrations of electrical concepts, such as the ball chain toy analogy.
USEFUL FOR

Students, educators, and professionals in physics and electrical engineering who seek to deepen their understanding of electron movement and current flow in conductive materials.

moment1337
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Electrons are moving in moves in all sorts of directions, causing the net electric charge to cancel out. But, when you apply a voltage, there's a small amount of electrons that will move towards the direction in the direction of the voltage. This is called the drift speed. Am I right? I read that the drift speed usually is 1/10000 of a second. How can you then obtain a current of 1 ampere, when 6.25*10^18 electrons has to move past a single point in one second, when the drift speed of the charge is that slow?
 
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moment1337 said:
a small amount of electrons
There are lots of free electrons in a typical wire.

moment1337 said:
How can you then obtain a current of 1 ampere, when 6.25*10^18 electrons has to move past a single point in one second, when the drift speed of the charge is that slow?
Lots of electrons!

See: Microscopic View of Electric Current
 
Oh I see now. So the drift velocity of a single electron might be very slow, but because there are 8.5 * 10^28 electrons in a wire point of the wire, you still can get a pretty high current flow?
 
moment1337 said:
Oh I see now. So the drift velocity of a single electron might be very slow, but because there are 8.5 * 10^28 electrons in a wire point of the wire, you still can get a pretty high current flow?

200px-Newtons_cradle_animation_book_2.gif

Have you seen this toy? It demonstrates the concept nicely. The time from an ball enters the ball chain to the end ball bouncing out is very short - but the internal balls (like the electrons in the wire) hardly move at all.
 
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Svein said:
200px-Newtons_cradle_animation_book_2.gif

Have you seen this toy? It demonstrates the concept nicely. The time from an ball enters the ball chain to the end ball bouncing out is very short - but the internal balls (like the electrons in the wire) hardly move at all.

Bravo Svein. This question comes up frequently on PF. That little video you posted explains it better than 10,000 words.
 
moment1337 said:
Oh I see now. So the drift velocity of a single electron might be very slow, but because there are 8.5 * 10^28 electrons in a wire point of the wire, you still can get a pretty high current flow?
Exactly.
 

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