Iron(II) sulfide or ferrous sulfide (Br.E. sulphide) is a chemical compound with the formula FeS. In the oil/gas industry, iron sulfides are often present in a sour system due to reaction between corrosion products and hydrogen sulfide.
A material that conducts (see conduction) electricity poorly or not at all. If a voltage is applied to a dielectric, the atoms in the material arrange themselves in such a way as to oppose the flow of electric current. Glass, wood, and plastic are common dielectrics. (See insulator.)
In physics, dielectric relaxation refers to the relaxation response of a dielectric medium to an external, oscillating electric field. This relaxation is often described in terms of permittivity as a function of frequency, which can, for ideal systems, be described by the Debye equation.