Electrotechnics: Basics


Mechanisms conduction electrical current in various media

Where there may be free charge carriers, where possible electric current. An elementary particle - an electron has a negative charge on the sign, this particle is so small that it is able to penetrate anywhere. In addition to her, there are other particles, such as photons. You can safely say that the existence of electrical current may everywhere. We live in a world of electric currents and magnetic phenomena.

Conductors of electricity

In physics are distinguished substance and vacuum, that is such a part of the space in which there is no substance, but may be present subatomic particles such as electrons or photons, that can react to electromagnetic fields.

What substances are they? First of all we are interested in their electrical properties, that is, the presence of free charge carriers.

Metals and their alloys. Hard graphite

First of all, it should be noted metals and their alloys, which are present in abundance of free charge carriers - electrons. Also here include such material as graphite, carbon in a solid crystallized form. Such substances are called conductors and their use to make electric circuits, as well as heating elements. Conventional incandescent lamps, which is used for lighting, is an excellent example of the current in the metal. There are very tiny wires, for example, in cell phones. They also exist in the current metals. The conductors of electrical current is called the conduction current.

Electrolytes and melts. Conductors of the second kind

Electric current in the electrolyte Electric current in gases

The next class of materials in which electrical current can exist - it melts and solutions. These include all electrolytes, such as aqueous solution of sodium chloride (NaCl), hydrochloric and sulfuric acids, bases, etc. Refers melts under liquid phase substance, for example, the same common salt may be melted and pass electric current through it. If a copper wire which is a good conductor to melt, then it would no longer be current conduction, and the current in the melt. This current and namely - electrical current in solutions and melts.

The gaseous phase of the substance. The current in plasma

In addition to the solid and liquid phase states of substance, there is also two of his condition. This gaseous phase, and the state of the plasma. Atmospheric air is a poor conductor electrical current, and simply referred to as an insulator. Normally, the gases are nearly always dielectrics, as they have no free charge carriers. However, in a gaseous atmosphere may flow current and this current is called - an electric current in the gases. Usually this current is accompanied by ionization, which may lead the gas into a plasma state.

It must be remembered that the flame of the fire - this is partially ionized gas, and therefore it is possible the flow of electric current. Flames of fire conducts and this must be kept in mind when working with electrical equipment. You should also distinguish between types of plasma. One type - high temperature (arc, flame), another kind - the low-temperature (current Tesla, a small spark in discharges).

Electric current in semiconductors

Is another class of substances - are semiconductors. This substance having a crystal structure in which impurities are introduced, atoms other substances. As a result, the main crystal, for example silicon, having the dielectric due to impurities is changing its electrical properties. Depending on which and how many impurity introduced, a new composite material will respond differently to the electric field. These substances are called semiconductors because of impurities formed in them either an excess of free charges or their deficiency. A whole class of devices based on semiconductors - that's electronics and microelectronics. Current in such substances called - electric current in semiconductors. Semiconductors occupy an intermediate position on the characteristics of conductivity and resistance between conductors and insulators.

CPU semiconductor

Vacuum conducts electricity

There is another class of non-substance, in which there may be electrical current. This transfer current, or a current in vacuo. By and large, 100% vacuum does not exist in reality, because there are certainly some particles as protons and neutrons, which are flying into the void. Even a single proton - it is "unfinished" a hydrogen atom.

Electronic lamp - vacuum device

In the space between the Sun and the Earth there is always a current in a vacuum. First of all - a stream of particles with an electrical charge. The source of these charges is the sun. At the same time the earth has an electric charge, and moves along the ecliptic, and hence there is a change in point of space charge per unit time.

This current is called - current transfer, or else the Convention's current. Available example of such a current is a vacuum tube in which emitted from the heated cathode and practically free electrons moving in vacuum to the anode. This phenomenon is called thermionic emission.

Date: 02.01.2016

© Valentin Grigoryev

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