normalconducting

Normal-conducting, or a normal conductor, refers to a material that carries electric current with finite resistivity, as opposed to superconductors which exhibit essentially zero resistance below a critical temperature. In ordinary conductors, current is carried by charge carriers that drift under an applied electric field, and the current-voltage relationship is described by Ohm's law in practice: V = IR. The conductivity σ is the reciprocal of resistivity ρ and depends on temperature, impurities, and crystal structure.

Common normal conductors include metals such as copper, aluminum, gold, and silver. Their resistivities at room temperature are about 1.6–2.7 × 10^-8 Ω·m. As temperature lowers, resistivity generally decreases due to reduced lattice vibrations, but a residual resistivity from impurities remains. Semiconductors also conduct but with conductivities that are highly sensitive to temperature and dopant levels, distinguishing them from typical metallic conductors.

The Drude model provides a simple picture: electrons accelerate under an electric field and scatter off impurities and phonons, giving a finite average drift velocity. At high frequencies, current tends to flow near the surface (skin effect), increasing apparent impedance. In power and high-frequency applications, resistive heating (I^2R losses) and electromigration in metal interconnects are practical limitations.

Normal conductors are contrasted with superconductors, which carry current with zero DC resistance and exhibit the Meissner effect below their critical temperature. Normal-conducting materials do not remove magnetic fields and require finite energy dissipation management in devices and systems.