Éléktrostatika: Béda antarrépisi

The [[electric field]] (in units of [[volt]]s per meterméter) is defined as the force (in [[newton]]s) per unit charge (in [[coulomb]]s). From this definition and Coulomb's law, it follows that the magnitude of the electric field ''E'' créated by a single point charge ''Q'' is

The [[triboelectric effect]] is a type of contact electrification in which certain materials become electrically charged when coming into contact with another, different, material, and are then separated. The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, and other properties. It is therefore not very predictable, and only broad generalizations can be made. Amber, for example, can acquire an electric charge by friction with a material like wool. This property, first recorded by [[Thales of Miletus]], suggested the word "electricity", from the Greek word for amber, èlectrònélectròn. Other examples of materials that can acquire a significant charge when rubbed together include glass rubbed with silk, and hard rubber rubbed with fur.

Charge generation incréases at higher fluid velocities and larger pipe diametersdiaméters, becoming quite significant in pipes 8 inches or larger. Static charge generation in these systems is best controlled by limiting fluid velocity. The British standard BS PD CLC/TR 50404:2003 (formerly BS-5958-Part 2) Code of Practice for Control of Undesirable Static Electricity prescribes velocity limits. Because of its large impact on dielectric constant, the recommended velocity for hydrocarbon fluids containing water should be limited to 1 m/sec.