How fast is electricity?

How fast is electricity?

2020-08-16 14:58



The electricity we use in our daily life is transported to our homes by wires and cables from distant power plants. That's during such a long transportation distance, for example, "sending electricity from the west to the East", will power transmission be delayed due to distance? Some people always say that electricity is fast. How fast is electricity?



1. First of all, let's talk about how the wires deliver electricity:

A conductor such as a wire can conduct electricity because there are electrons in it. Before the circuit is connected, they are free and move irregularly in the conductor. As soon as the circuit is connected, these electrons will flow in an orderly and directional manner as if they hear the command. At this time, the migration speed of electrons is called "electron drift velocity". It's not a racer's drift, on the contrary, it's not fast at all!

The drift velocity of electrons in a conductor is related to the mass and length of the conductor,all in all, it's very slow,most of the time it's less than 1 millimeter per second.It's slower than a snail!In this case, when we turn on the light switch, we have to wait at least several decades for the light to come on,But the fact is, as soon as we turn on the lights, the lights go on. What's the reason?



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

As soon as the circuit is connected, an electric field will be formed around the conductor to promote the orderly flow of electrons, thus forming a current. The information forming the electric field will quickly spread around the conductor in the form of electromagnetic waves. The velocity of the electromagnetic wave is basically close to the "most runnable" material found so far-----The speed at which light travels in a vacuum.It's about 300000 kilometers per second. This is what we usually call "the speed of electricity."


For example:

There was a long line of students ready to line into the gymnasium.At first, the team was loosely blocked at the gate of the gymnasium. Everyone either chased and played in groups or ran around like a headless fly.Suddenly, the stern teacher came!He was very angry when he saw that the team was so disorganized and undisciplined. He yelled: "gather for me quickly and get up!"There were especially afraid of the teacher. As soon as there heard the order, quickly and orderly lined up to enter the gymnasium.

This story can correspond to the process of electrical transmission.

Why does electricity have the same speed as light?From the above analysis, we can draw a conclusion:What we call the speed of electricity is basically the speed of electromagnetic wave propagation,the number one on the speed charts is light,It's an electromagnetic wave,It's just that we can see it. Do you understand now?



So, now, we don't have to worry about the problem that the wire is so long that the electricity can't be transmitted in time.We know that the circumference of the earth's equator is 40000 kilometers. According to the speed of electricity, it can go around the earth eight times a second.


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