Sähköjohtimeen

Sähköjohtimeen, often translated as electrical conductor, is a material that allows electric charge to flow easily through it. This property is due to the presence of mobile charge carriers, typically electrons, within the material. Metals are the most common examples of conductors due to their atomic structure, where valence electrons are loosely bound and can move freely.

The ability of a material to conduct electricity is measured by its electrical conductivity, denoted by the symbol sigma (σ). High conductivity indicates that a material is a good conductor, while low conductivity means it is a poor conductor or an electrical insulator. The reciprocal of conductivity is resistivity (ρ), which measures a material's opposition to the flow of electric current.

Common electrical conductors include copper, aluminum, silver, and gold. Copper is widely used in electrical wiring due to its excellent conductivity and relatively low cost. Aluminum is another popular choice, especially in overhead power lines, for its lighter weight and good conductivity. Silver is the most conductive metal, but its high cost limits its widespread use in general electrical applications. Gold, while less conductive than silver, is highly resistant to corrosion and is often used in electrical connectors and contacts where reliability is crucial.

In contrast to conductors, electrical insulators are materials that resist the flow of electric current. Examples of insulators include rubber, plastic, glass, and ceramics. These materials have tightly bound electrons that cannot easily move, thus preventing the passage of electric charge. Understanding the difference between conductors and insulators is fundamental to electrical engineering and the safe design and operation of electrical systems.