Electrical contacts Electrical contacts An electrical contact is an electrical circuit component found in electrical switches, relays, connectors and circuit breakers. Each contact is a piece of electrically conductive material, usually metal. When a pair of contacts touch, they can pass an electrical current with a certain contact resistance, dependent on surface structure, surface chemistry and contact time; when the pair is separated by an insulating gap, then the pair does not pass a current. When the contacts touch, the switch is "closed"; when the contacts are separated, the switch is "open". The gap must be an insulating medium such as air,
Electrical length Electrical length In telecommunications and electrical engineering, electrical length (or phase length) refers to the length of an electrical conductor in terms of the phase shift introduced by transmission over that conductor at some frequency. Depending on the specific usage, the term "electrical length" is used rather than simple physical length to incorporate one or more of the following three concepts: The first usage of the term "electrical length" assumes a sine wave of some frequency, or at least a narrowband waveform centered around some frequency "f". The sine wave will repeat with a period of "T" = 1/"f". The