Electrical resistivity and conductivity 1 Ω⋅m. Electrical conductivity or specific conductance is the reciprocal of electrical resistivity, and measures a material's ability to conduct an electric current. It is commonly represented by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) or γ (gamma) are also occasionally used. Its SI unit is siemens per metre (S/m). In an ideal case, cross-section and physical composition of the examined material are uniform across the sample, and the electric field and current density are both parallel and constant everywhere. Many resistors and conductors do in fact have a uniform cross section with a uniform
Electrical tape Electrical tape Electrical tape (or insulating tape) is a type of pressure-sensitive tape used to insulate electrical wires and other materials that conduct electricity. It can be made of many plastics, but vinyl is most popular, as it stretches well and gives an effective and long lasting insulation. Electrical tape for class H insulation is made of fiberglass cloth. A wide variety of electrical tapes is available; some for highly specialized purposes. "The primary tapes used in electrical applications are vinyl, rubber, mastic, and varnished cambric." Electricians generally use only black tape for insulation purposes. The other colors are used