Today one of the most important characteristics of any material is its electrical resistance.This is due to the unprecedented in human history, the spread of electric cars, will force a different way to look at the properties of the surrounding materials such as artificial and natural origin.The term "electrical resistance" has become as important as the specific heat and so forth. It applies perfectly to everything that surrounds us: water, air, metal, even a vacuum.
Every modern person should have an idea about this characterization of materials.To the question "what is the electric resistance" can be answered only if you know the meaning of the term "electrical current".With this and start ...
material manifestation of energy is the atom.It includes all of them connected in groups.The current physical model argues that the atom is like a scale model of the stellar system.In the center is the core, which includes two types of particles: neutrons and protons.The proton carries a positive electrical charge.At different distances from the nucleus in circular orbits rotate other particles - electrons carry a negative charge.The number of protons always corresponds to the number of electrons, so that the total charge is zero.The distance from the nucleus is the electron orbit (valence), the weaker the force of gravity, hold it in the structure of the atom.
The current generation car releases the magnetic field of the orbits of the valence electrons.Since the nucleus of an atom that has lost an electron, is the "extra" proton, the force of gravity to "rip" the other valence electron from the outer orbit of the neighboring atom.In the process it lured the whole structure of the material.The result is the motion of charged particles (atoms with a positive charge and a negative free electrons), which is called an electric current.
material, the structure of which the electrons are the outer orbits can easily leave the atom, called the conductor.Its electrical resistance is small.This group metals.For example, for the production of wires mainly use aluminum and copper.According to Ohm's law, the electrical resistance of the conductor is the ratio of the voltage created by the generator to the power flowing current.Incidentally, the resistance is measured in "ohms".
easy to imagine that there are materials in which the valence electrons is very small or highly atoms distant from each other (gas), and therefore their internal structure can not allow the passage of current.They are called insulators and are used to isolate the conductive lines in electrical engineering.Electrical resistance in them is very high.
Everyone knows that wet insulator begins to conduct electricity.In light of this fact becomes particularly interesting question of "whether there is electrical resistance of the water."The answer is controversial: yes and no.As mentioned earlier, if the material of the valence electrons is little, and the structure is composed of voids greater than the particles (recall the periodic table and hydrogen with a single electron orbit), the conductivity in ordinary conditions can not exist.Under this description perfect water: compound of two gases that we call fluid.Indeed, being completely free of dissolved impurities, it is a very good insulator.But since the nature of water are always present in the salt solution, the electrical conductivity is provided by them.At its saturation level affects the temperature of the solution and (aggregation state).That is why a clear answer to the question can not be, because the water is different.
