How fast moving electric current through the wires

You probably immediately say that the speed of the electric current is equal to the speed of light and you will be wrong. In this article I will explain with a simple example, how and at what speed it is moving electrical current through the wires.

Let's take for example, simulate the following scenario:

Let us have the bulb connected to the constant power supply two-wire shielded cable, the length of the cable is 10 kilometers.

Now if we turn on the switch in this circuit, the bulb will light up 10 km / 300 000 km / s, with 10 km - is the length of our conductor and 300,000 km / s - is the velocity of propagation of an electromagnetic wave (light) in vacuo.

That is, the calculations, it turns out, the bulb lights up by 0.00003333 seconds, or 33,333 microseconds (shall not be accepted by conductor capacitance). From this it follows that "the movement of electrons" spread over the guidewire with the speed of light.

But the fact that the electrons begin to move one after another with the speed of light does not imply that they are moving in a conductor with the same speed.

Here, the speed of light, this is the rate at which the charged particles begin to move one behind the other, and move through a conductor they can at a rate of only a few millimeters per unit time.

Unclear? Let me explain why.

So we closed the circuit by pressing the switch. At this time, the electrons begin to leave the negative terminal of our you capacitor, thus there is a reduction in electric field in the dielectric of the capacitor and the electrons (from the connected conductor) begin to go positive terminal capacitor.

Thus, the potential difference between the capacitor plates decreases. And due to the fact that the electrons in the adjoint conductor portion into motion, their vacant space occupied by the electrons from the adjacent portion of wire (by electromagnetic fields closed chain).

This process of moving spreads further through the conductor, and after a certain time reaches our joint bulb and the flowing current causes it to glow.

It turns out that the change of the electric field in the conductor is distributed immediately, but do the charged particles have a much lower rate.

The analogy with running water

Let's for ease of understanding the analogy with the plumbing.

Imagine the following scene: you run the water pump, also located far outside the city and in just a fraction of seconds (pressure change propagates at an average speed of 1400 km / s) have from the beginning of the water flow pipe. But this is not the same water that has just passed through the pump, "crush" the water molecules spread with great speed, and the molecules themselves move at a much slower rate.

And with the movement of electric current.

And how AC

Well, it seems to be a constant current is more or less become clear and can also be a second logical question: And how are things with alternating current?

In fact, the difference here lies only in the fact that the alternating current changes direction with a frequency of 50 Hertz at a time. But it all depends on the speed of the same factors as in the case of direct current.

Summary and Conclusions

So, let's revisit the current. So, if the conductor is not affected by the electromagnetic field, the motion of electrons inside the wire takes place completely in a chaotic manner.

Once the conductor is an electric field effect, depending on factors such as temperature conductor material, the potential difference, electric current speed may vary from 0.6 to 6 millimeters in one unit time. As you can see, this value is very far from the speed of light. And it is calculated by the following formula:

Where n - the density of free carriers, S - conductor cross-sectional area, e - the charge of the particles, I - current intensity.

That's all I wanted to tell you about the velocity of the electric current through the wires. If the article was useful to you, you will appreciate it Like. Thank you for your attention!