Weerstand

Electrical resistivity is an intrinsic property of a material, describing how effectively it resists the flow of charges.

Resistivity is the reciprocal of electrical conductivity and can be defined in terms of the electrical field and the current density. The SI unit of resistivity is the ohm-meter.

Good conductors have a high conductivity but a low resistivity, whereas good insulators have a low conductivity but a high resistivity.

Temperature influences the resistivity of some materials. In many materials, the dependence is approximately linear and can be modeled using a linear equation where ρ is the resistivity of the material at a temperature, α is the temperature coefficient of the material, and ρ₀ is the resistivity at room temperature.

The resistivity of some materials, such as copper, increases as temperature increases; in others, like carbon, resistivity decreases as temperature increases.

In semiconductors, the temperature coefficient is negative, implying that resistivity decreases as temperature increases.