Modern civilization exists partly due to electric energy, which man has managed to put at his service. Electrical appliances allow us to establish a sound and visual connection between distant points, they scatter the darkness of the night and warm us in the winter.
It makes no sense to list all the uses of electricity, because everyone knows this. Nevertheless, for some people who do not have an electrical education, it remains a mystery why electrical appliances have a double wire. Indeed, the power plugs of household electrical appliances are equipped with just two pins (you can ignore the auxiliary grounding contact), and not three or four. Perhaps this is done in order to save (after all, two is less than three)? Let's get it right.
Picking up a textbook
To answer the question: “Why do electrical appliances have a double wire?” - you need to remember the basics of electricity. Many teachers, defining the term “electric current”, compare it with the flow of water.
Such a comparison is quite acceptable, of course, with certain reservations. We use it too.
Imagine a channel through which water flows. In one of the sections placed the blades of a water mill, converting the natural forces of movement of water masses into useful work. Obviously, after passing through the blades, the speed decreases slightly. This value depends on a number of factors, therefore, it may be invisible "by eye", but it is. Obviously, the blades will rotate only if the fluid moves. And this, in turn, is possible when there is a third-party effect (height difference or discharge). In this analogy example, the directed water flow is an electric current, the channel is a conductor, and the mill is a device with a certain resistance. It is enough to plug the device into a power outlet and press the power button, as one of the wires will flow current.
Having transformed into another type of energy (having completed the work), he will continue to move along another wire, returning to the general network. That is why the answer to the question “why do electrical appliances have a double wire” is simple: it cannot be otherwise, since at least two points are needed for the current of charged particles. Note that they must be different. That is, if in the channel there is no difference in heights between the start and end points, then the displacement of the masses of water will not occur.
Practice
If we talk about the intra-house electrical network of alternating current, then depending on the connection, one of the wires is phase - it is on it that the excess potential is located , and the second is zero. The charge from the phase wire, having fallen on one of the pins of the plug of the electrical appliance, does the work and returns to the neutral wire by the corresponding contact. Sometimes people who are interested in why electrical appliances have a double wire, give an example of a system with three and four conductors. Indeed, there are some. In this case, there are several phase wires.
The explanation of the processes occurring in such chains is more complicated and is not given in this article. Two wires are also involved in the DC circuits: positive (excess of ions) and negative (electrons).
Transmission medium
In order for the current to “reach” our devices, it is necessary to take care of the “road” for it. It is a metal insulated conductor or wire. Several wires in common insulation make up the cable. Sometimes these terms are confused. So, for example, the name “SIP-wire” arose, although in the abbreviation the letter “P” just means such a conductor.
This is a fairly new product, so dwell on it in more detail. The so-called SIP cable in our country has appeared recently. In fact, it consists of several wires, the insulation of which is soldered to each other, which forms a single structure. The peculiarity of SIP is that it does not require wire for suspension, as it is self-supporting. In addition, its insulation withstands open air for at least 40 years in a temperate climate.