Current and Speed of Light: True or False?

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Discussion Overview

The discussion revolves around the speed at which electrical current travels, particularly in relation to the speed of light. Participants explore concepts related to electromagnetic fields, electron drift speed, and the propagation of signals in electrical circuits.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that electrical current travels at the speed of light, while others contest this claim.
  • One participant defines "current speed" and distinguishes between the speed of electromagnetic waves in a wire and the drift speed of electrons, which is much slower.
  • There is a discussion about whether the speed of a "signal" is dependent on the movement of electrons or protons in a wire.
  • Another participant notes that while electromagnetic fields propagate at the speed of light, the actual propagation of signals involves the movement of charge carriers, which occurs at a different speed.
  • One participant describes a conceptual model involving neutral atoms and the displacement of electrons, questioning how the electric field interacts with matter and whether this process takes time.

Areas of Agreement / Disagreement

Participants express conflicting views regarding the speed of electrical current and the relationship between electromagnetic fields and the drift speed of charge carriers. No consensus is reached on these points.

Contextual Notes

Participants highlight the distinction between the propagation of electromagnetic fields and the drift speed of electrons, indicating a need for clarity on definitions and assumptions regarding "current speed." Unresolved questions remain about the mechanisms of signal propagation in electrical circuits.

Who May Find This Useful

This discussion may be of interest to those studying electrical engineering, physics, or anyone curious about the nature of electrical currents and electromagnetic theory.

kapil phyreak
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i read somwhere that current travels with speed of light...is it true?
 
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Electrical current travels at speed of light.
Water currents and air currents do not.
 
Define "current speed".

When you switch the light on, electromagnetic wave in the wire travels at the speed of light, but electrons drift speed is in the range of mm/s (or something in this range).
 
Bloodthunder said:
Electrical current travels at speed of light.
Water currents and air currents do not.

This is NOT true. Current does not travel at the speed of light.

@Borek: The e/m fields propagate at the speed of light, but isn't the speed of a "signal" dependent on how fast the electrons/protons move to propagate the electric field along a wire?
 
Pengwuino said:
The e/m fields propagate at the speed of light, but isn't the speed of a "signal" dependent on how fast the electrons/protons move to propagate the electric field along a wire?

I always thought electric field propagates just like e/m filed - at the speed of light, is it in this regard in any way different from e/m field?
 
Well, the "electric field" is part of the "electro-magnetic field"- but it isn't the field that propogates, it is waves in the electromagnetic field that propagate at the speed of light. In fact, light is waves in the electromagnetic field.
 
Borek said:
I always thought electric field propagates just like e/m filed - at the speed of light, is it in this regard in any way different from e/m field?

The way I'm imagining it is a neutral atom having an electric field applied. The field proceeds to displace the electrons so that some sort of multipole moment is formed which creates a field to do the same to the next atom and so on. In my mind, if this is true, the formation of the moments takes take to occur. I'm really not sure how it actually works though.
 

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