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Movement speed of electricity in cable, is same as speed of light in space? In other words, electricity moves in usual electro cable aproximatelly 300 000 km/second ?

Oto Shavadze
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    You should clarify what exactly you want to know. The speed of the actual electrons through the cable, or how fast the response of the electrons is to an applied voltage. These are different by quite a bit, as the electrons move through the circuit quite slowly, even by human standards. – tmwilson26 Oct 26 '15 at 14:14
  • Remember that in classical electrodynamics, the energy transmitted from the source to the load in a current-carrying wire is not in general transmitted by the electrons themselves; it is carried by the electromagnetic field generated by accelerating charges (see https://en.wikipedia.org/wiki/Poynting_vector).

    In any circuit with loss, you must actually expend energy to overcome the loss and get the electrons moving such that the field is generated.

     – MattyZ Oct 26 '15 at 15:00
  • Or do you want to know the propagation speed of a signal in a cable (like a pulse or a superposition of sine waves)? – Bill N Oct 26 '15 at 20:41

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Sorry for a low-tech explanation.

It is like a metal pipe filled with water. If you put more water in one end, it (almost) immediately comes out the other end, because the pipe cannot expand, so some water has to come out to make room for the water that goes in.

When I say (almost) immediately, it depends on the speed of sound in water. It requires a pressure wave to convey the information from input to output.

Is the water moving at that speed? Of course not. It is moving slowly, at a speed that depends on the diameter of the pipe.

It's basically the same with electric charge carriers. The information travels from one end of the wire at a speed close to the speed of light, but not equal, because it is traveling in the conductor.

Mike Dunlavey
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There are two velocities to consider here. Firstly there is the velocity of propagation of the electromagnetic wave. As soon as you get a force on the first row of electrons on the cable, their displacement will create a force on the second row and so on. This chain reaction travels at the speed comparable with the speed of light (between 0.42c and 0.72c) and it's responsible for the time it takes between you flipping the switch and having electricity flowing on the light bulb.Wikipedia about velocity factor

There is also the drifting speed of the electrons themselves, which is very very slow. As an illustrative example, consider the case of copper with a current of 5A and a cross section of 0.5 mm^2 that results in each electron moving at a speed around 0.75mm/s.

SlySherZ
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It depends on voltage, material; etc. But as an example, for a 12-gauge copper wire carrying a 10-ampere DC current, the speed of electric current (average electron drift velocity) is about 80 centimeters per hour or about 0.0002 meters per second.

  • It's not clear if the OP was asking the question that this answers, or if he was asking about the speed of propagation of a voltage or current wave or pulse. – garyp Oct 26 '15 at 14:24