The value of metals is directly determined by their chemical and physical properties. In the case of an indicator such as electrical conductivity, this connection is not so straightforward. The most conductive metal, when measured at room temperature (+20 ° C), is silver.
But the high cost limits the use of silver parts in electrical and microelectronics. Silver elements in such devices are used only in case of economic feasibility.
The physical meaning of conductivity
The use of metal conductors has a long history. Scientists and engineers working in the fields of science and technology that use electricity have long decided on materials for wires, terminals, contacts, printed circuit boards , etc. To determine the most conductive metal in the world, a physical quantity called electrical conductivity helps.
The concept of conductivity back to electrical resistance. The quantitative expression of conductivity is related to the unit of resistance, which in the international system of units (SI) is measured in Ohms. The unit of electrical conductivity in the SI system is Siemens. The Russian designation for this unit is Cm, the international one is S. The electrical conductivity of 1 Cm has a section of the electrical network with a resistance of 1 Ohm.
Conductivity
A measure of the ability of a substance to conduct an electric current is called electrical conductivity. The highest conductivity is found in the most electrically conductive metal. This characteristic can be determined for any substance or medium instrumentally and has a numerical expression. The electrical conductivity of a cylindrical conductor of unit length and unit cross-sectional area is related to the specific resistance of this conductor.
The systematic unit of conductivity is siemens per meter - S / m. To find out which metal is the most electrically conductive metal in the world, it is enough to compare their specific conductivity, determined experimentally. You can determine the resistivity using a special device - a microohmmeter. These characteristics are inverse.
Metal conductivity
The very concept of electric current as a directed flow of charged particles seems more harmonious for substances based on crystal lattices characteristic of metals. Carriers in the event of an electric current in metals are free electrons, not ions, as is the case in liquid media. It was experimentally established that when a current occurs in metals, there is no transfer of particles of matter between the conductors.
Metallic substances are distinguished from others by more loose bonds at the atomic level. The internal structure of metals is characterized by the presence of a large number of "lonely" electrons. which at the slightest impact of electromagnetic forces form a directed flow. Therefore, it is not in vain that metals are the best conductors of electric current, and it is precisely such molecular interactions that distinguish the most conductive metal. Another specific property is based on the structural features of the crystal lattice of metals - high thermal conductivity.
Top best metal conductors
4 metals of practical importance for their use as electrical conductors are distributed in the following order relative to the specific conductivity measured in S / m:
- Silver - 62.5 million.
- Copper - 59.5 million.
- Gold - 45.5 million.
- Aluminum - 38,000,000.
It can be seen that the most electrically conductive metal is silver. But like gold, it is used to organize an electrical network only in special specific cases. The reason is the high cost.
But copper and aluminum - the most common option for electrical appliances and cable products due to the low resistance to electric current and affordability. Other metals are rarely used as conductors.
Factors affecting the conductivity of metals
Even the most conductive metal reduces its conductivity if other additives and impurities are present in it. Alloys have a different crystal lattice structure than pure metals. It differs in violation in symmetry, cracks and other defects. Conductivity also decreases with increasing ambient temperature.
The increased resistance inherent in alloys is used in heating elements. It is no coincidence that nichrome, fechral and other alloys are used to make working elements for electric furnaces and heaters.
The most electrically conductive metal is precious silver, which is more commonly used by jewelers for minting coins, etc. But even in engineering and instrument engineering, its special chemical and physical properties are widely used. For example, in addition to use in units and assemblies with reduced resistance, silver spraying protects contact groups from oxidation. The unique properties of silver and alloys based on it often make its use justified, despite the high cost.