sähkönjohtavuudesta

Sähkönjohtavuus, often referred to as electrical conductivity, is a measure of a material's ability to conduct electric current. It quantifies how easily electric charge carriers, such as electrons or ions, can move through a substance when subjected to an electric field. Materials with high electrical conductivity allow charge to flow readily, while materials with low conductivity, known as electrical insulators, resist the flow of charge.

The inverse of electrical conductivity is electrical resistivity, which measures the opposition to current flow. The relationship is reciprocal: a highly conductive material has low resistivity, and an insulating material has high resistivity. Conductivity is typically denoted by the Greek letter sigma ($\sigma$) and its SI unit is siemens per meter (S/m).

The conductivity of a material depends on several factors, including its atomic structure, temperature, and the presence of impurities. Metals, such as copper and silver, are excellent conductors due to their free electrons. Semiconductors, like silicon, have conductivity levels between those of conductors and insulators, and their conductivity can be manipulated by doping. Insulators, such as rubber and glass, have tightly bound electrons that are not easily dislodged, preventing significant current flow. Understanding sähkönjohtavuus is fundamental in the design and application of electrical and electronic devices.