Definiciones de corriente, resistencia, resistividad, densidad de corriente y conductividad.
STREAM
Current or electrical intensity is the flow of charge per unit time through a material. It is due to the movement of electrons within the material. In the International System of Units it is expressed in C/s (coulombs per second), a unit called ampere. An electric current, since it is a movement of charges, produces a magnetic field, a phenomenon that can be exploited in the electromagnet.
RESISTIVITY
Its value describes the behavior of a material against the passage of electric current, thus giving an idea of how good or bad a conductor it is. A high resistivity value indicates that the material is a poor conductor while a low value indicates that it is a good conductor.
ELECTRICAL RESISTANCE
The electrical resistance of an object is a measure of its opposition to the passage of current.
Discovered by Georg Ohm in 1827, electrical resistance bears a conceptual resemblance to friction in mechanical physics.
The unit of resistance in the International System of Units is the ohm (Ω). For its measurement in practice there are various methods, among which is the use of an ohmmeter. In addition, its reciprocal quantity is the conductance, measured in Siemens.
CURRENT DENSITY
Electric current density is defined as a vector quantity having units of electric current per unit area, i.e., current per unit area. Mathematically, current and current density are related as:
ELECTRICAL CONDUCTIVITY
Conductivity depends on the atomic and molecular structure of the material, metals are good conductors because they have a structure with many electrons with weak bonds and this allows their movement.
Conductivity also depends on other physical factors of the material itself and temperature.
Conductivity is the inverse of resistivity, hence , and its unit is the S/m (siemens per meter) or Ω-1-m-1.
Usually the magnitude of the conductivity (σ) is the proportionality between the electric fieldE and the conduction current density J :