How fast does electricity travel? Compared to the speed of light?

Nowadays, the voltage levels of the grid are higher and the transmission lines are longer and longer, and a single UHV is often thousands of kilometers long. The longest transmission line in the world is 3,300 kilometers long.

Add in the city's main grid, distribution grid, etc., and the line from the power plant to your home may have to be 4,000 kilometers.

Can this electricity be delivered any time soon? Will there be delays?

That's not to worry about, because the speed of electricity is very, very fast, almost as fast as the speed at which light, the best thing ever discovered, travels through a vacuum, which is about 300,000 kilometers per second.

So it takes about 0.03 seconds for electricity to travel 10,000 kilometers. The amount of time you can't even blink (0.2-0.4 seconds) is negligible.

Why can electricity run so fast?


First, how power lines carry electricity from a distance of several meters, hundreds of meters, or even thousands of kilometers:

A conductor, such as a wire, conducts electricity because there are electrons in it, and until they are connected to the circuit, they are free and move around erratically in the conductor. As soon as the circuit is switched on, these electrons begin to flow in an orderly manner as if on command, creating a current 39bet-kết quả bóng đá-kết quả xổ số miền bắc-kèo bóng đá -soi cầu bóng đá-đặt cược. This average of the ordered flow of electrons is called the "electron drift velocity". This is not a racecar's drift, it's not fast at all!

The speed at which electrons drift through a conductor depends on factors such as conductor mass and length, and is generally very, very slow, in many cases less than 1 mm/SEC. It's slower than a snail! How many centuries would it take for the electrons from the power plant to float to my house...

The speed of the electron's drift is so slow, of course, that it cannot be the "speed of electricity" that we usually say is about the speed of light.


In fact, there is another speed in the transmission of electricity:

The propagation process of "electricity" is roughly like this: before the circuit is connected, although there are free electrons everywhere in the metal wire, there is no electric field in the wire. The whole wire is in electrostatic equilibrium, and the free electrons only do irregular thermal movement without directional movement. Of course, there is no current in the wire. When the circuit is connected, the electric field will spread the information about the change of the field source at the speed of light, so that the electric field will be quickly established in the wires everywhere in the circuit, and the electric field will push the local free electrons to drift and form the current. This electromagnetic wave travels close to the speed of light. This is the real "speed of electricity".

Raise your hand if you don't see it. We can also think of it this way.​

Small theater

There was a long, long line of students, ready to enter the gym. At first, before the teacher arrived, the team was scattered in front of the gym, chasing each other in small groups or running around like headless chickens. Suddenly, the strict teacher came! He saw the team so unorganized and undisciplined, especially angry, shouted: "Hurry to my assembly, walk!" We are particularly afraid of the teacher, a command to quickly orderly begin to walk into the gym...

The above plot can correspond one to one with the process of electric transmission.

How can electricity travel at the same speed as light?

From the foregoing analysis, we can conclude that the speed of electricity is basically the speed of electromagnetic wave propagation.

And that's the point: light, which dominates the speed charts for years, is an electromagnetic wave, only it can be seen.

Do you understand now ~

So, for now, we don't have to worry about the wires being so long that the electricity can't be transmitted in time. We know that the circumference of the earth's equator is more than 40,000 kilometers, according to the speed of electricity, not a circle of 1 second...

That's plenty of speed for us!

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