Dielektrikumets

Dielektrikumet, or the dielectric, refers to a class of insulating materials that can be polarized by an electric field. In devices, dielektrikumet separate conductors and increase capacitance, enabling energy storage. The key parameter is the permittivity, ε, which relates electric displacement D to the electric field E by D = εE. Absolute permittivity ε = ε0εr, where ε0 is the vacuum permittivity and εr is the relative permittivity or dielectric constant. Different polarization mechanisms contribute to εr: electronic polarization, ionic polarization, and, in some materials, orientational polarization. Dielektrikumet also exhibit losses at alternating fields, quantified by the dielectric loss tangent, tan δ.

Dielectric strength describes how much electric field the material can withstand before breakdown and conduction occurs. This depends on material purity, temperature, humidity, radiation, and frequency. Typical dielektrikumet include air, glass, paper, ceramics, and polymers. Engineered dielektrikumet include polymer films used in capacitors, ceramic dielectrics in high-frequency circuits, and ferroelectric ceramics in some memory devices.

In capacitors, the dielectric increases capacitance by a factor εr; the energy density is u = 1/2 ε0εr E^2. Temperature and frequency influence εr and tan δ; many polymer dielektrikumet have low dielectric loss suitable for high-frequency applications, whereas ferroelectric dielektrikumet offer large εr but can be temperature-sensitive.