Bulkstrøm

Bulkstrøm is a term used primarily in physics and electrical engineering to describe the portion of electric current that flows through the interior, or bulk, of a material, as opposed to current that is confined to surfaces, interfaces, or nanoscale channels. The concept is tied to current density J, defined as the amount of charge passing through a cross-section per unit area per unit time. The total current I is the integral of J over the cross-sectional area of the material.

In homogeneous media, the bulk current is described by Ohm’s law in the form J = sigma E, where sigma is the bulk electrical conductivity and E is the electric field. The bulk conductivity reflects the density and mobility of charge carriers within the material’s interior. Surface effects and frequency can modify how current distributes. At DC and in sufficiently thick samples, bulk current dominates, while at AC or in thin films, surface currents or skin effects can become significant. In nanoscale devices, the distinction between bulk and surface or channel conduction can blur, and transport may be controlled by interfaces or defects.

Bulk current is a useful concept in materials science and electrical engineering for modeling transport properties, interpreting conductivity measurements, and designing components such as wires, films, and semiconductor devices. See also: electric current, current density, bulk conductivity, skin effect, surface conduction.