Conductivity – Definition, Formula, Unit

Conductivity Unit

All the electronic items that we use have a channel that lets the current move through them. Also, the electric conductivity is the measure the ability of a conductor to conduct electricity. Moreover, in this topic, you will study the conductivity definition, its formula, and the conductivity unit.


Electric conductivity refers to the measure of how electric current moves within a substance. Also, the greater the electrical conductivity within the material the higher the current density for a given applied potential difference.

In simple words, we can say that electrical conductivity is the ability of a substance to conduct electricity. Also, we can see it as the electrical conductance or conductivity of a material is important because some substance requires to conduct electricity and some not.

For example, the wire conductors need to let current flow as easily as possible. While, some other minerals required to restrict the flow of the current, as in the case of the resistor.

On the other hand, some other materials are required not to conduct electricity as in the case of the insulators.

conductivity unit

Basics of Electrical Conductivity

It is the ratio of the current density to the electrical field strength. Also, the greater the value of the conductivity, the lower the resistance it provides to the flow of electric current.

Moreover, the value of electrical conductivity depends on the ability for electrons or other charge carriers for example holes to move within the lattice of the material.

Furthermore, the highly conductive material such as copper allows the free flow of electrons within their molecular lattice. Moreover, there are free electrons within the lattice. Also, the process is vice-versa for low conductive material.

Conductivity Formula

The conductivity formula is the inverse of the resistivity that is:

\(\sigma = \frac{1}{\rho}\)

\(\sigma\) = refers to the electrical conductivity
\(\rho\) = refers to the resistivity

Conductivity Unit

The conductivity unit is Siemens per meter (\(S \cdot m^{-1}\)). Also, we used to refer it to as mho – that is the reciprocal of an Ohm and this is incidental by spelling Ohm backwards.

Furthermore, conductance is the reciprocal of resistance and one Siemens is equivalent to the reciprocal of 1 Ohm.

The \(14^{th}\) General conference on weights and measures in 1971 accepts the SI unit fo0r conductance. Also, Ernst Werner Von Siemens was the person on whom they name it.

Moreover, The SI unit name is derived from the proper name of the person that discovered which in this case is Siemens and is denoted with a capital (upper case) letter ‘S’.

In addition, we use the most common symbol of the lower case version of the Greek letter Sigma \(\sigma\), but on various occasions, we also use kappa, \(\kappa\) and gamma \(\gamma\).

Moreover, the SI unit of conductivity is most widely used and conductivity values are often stated in terms of their IACS (International Annealed Copper Standard) percentage value. In addition, the IACS was established in the year 1913 by the IEC (International Electrochemical Commission).

Besides, the conductivity of the annealed copper (5.80001 × 107 S/m) is an overview of 100 per cent IACS at \(20^{\circ} C\).

Furthermore, all the conductive values relate back to this conductive value. Also, it means that iron with the conductive value of 1.04 × 107 S/m, has a conductivity of approximately 18 per cent of that of annealed copper and is certain as 18 % IACS.

From the time of introduction of the standards, the metallic processing methods are now of better quality.

Some modern copper products now often have conductivity values higher than 100 % IACS because now we can remove more impurities from the metal.

Solved Example for You

Question. Which of the following is the most conductive metal?

A. Silver

B. Aluminium

C. Copper

D. Gold

Answer. The correct answer is option C.

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