The presentation prepared by the student of the group Marupov Nuruhammad on the subject of electrical engineering and structural materials

Dielectric wetting, physical, chemical, mechanical properties.

• Dielectrics (eng. electric - electric) are materials (substances) that do not conduct electric current; specific electrical resistance — 107-1020 Ohm, dielectric permittivity — 4-104. Dielectrics conduct electricity 1015-1020 times worse than conductors. The term "dielectrics" was introduced to science by Michael Faraday. All non-ionized gases, some liquids, and solids are dielectrics. Dielectrics can be divided into polar dielectrics and non-polar dielectrics in cases where there is no external electric field effect. In this case, the dipole moments of molecules of dielectrics are zero (non-polar molecules) or randomly distributed along directions in space (polar molecules). In both cases, the total electric moment of dielectrics is zero. Polarization depends on electric field strength, voltage, electrical property of medium. Polar dielectrics include alcohol, pure water; Non-polar dielectrics include inert gases, oxygen, hydrogen, benzene, polyethylene, etc. enters.

• Physical properties of dielectric
• Knowing the density of the dielectric is necessary to determine the need for the material, its volume or mass in the production of the product. Density is determined by the ratio of the body mass m to its volume V:
• kg/m3 (4.1)
• In organic materials = (0.5-1.5) 103kg/m3, and in inorganic materials = (2.5-1.5)103kg/m3. The hygroscopicity of the material is determined by keeping the object in water for a certain time:
• (4.2)
• where m1 is the mass of the dry sample, m2 is the mass of the sample after holding it in water for a certain time (g). This quantity helps in evaluating the moisture resistance of the dielectric.

Basic concepts of dielectric materials

• DIELECTRIC, substances that conduct electricity poorly. The term "dielectric" was introduced by M. Faraday to indicate substances that enter the electrostatic field. When any substance is placed in an electric field, electrons and atomic nuclei move in this field. As a result, part of the charges are directed in such a way as to form an electric current. The remaining charges are redistributed, so the "centers of gravity" of positive and negative charges change relative to each other. Second, they talk about the polarization of matter. Depending on which of these two processes (polarization or electrical conductivity) prevails, substances are divided into dielectrics (all non-ionized gases, some liquids and solids) and mercury (metals, electrolytes, plasma).
• The electrical conductivity of dielectrics is very small compared to metals. Electrical resistance of dielectrics is 10 8 -10 17 Ohm · cm, metals - 10 -6 -10 -4 Ohm · cm.
• Classical physics explained the quantitative difference in the electrical conductivity of dielectrics and metals by the presence of free electrons in metals, while in dielectrics all electrons (belonging to individual atoms) and the electric field did not tear, but slightly loosened them.