What are some fluids with the lowest conductivity

Electrical conductivity: from insulators to superconductors

What does electrical conductivity mean?

Electrical conductivity is also known as conductivity. It is a quantity within physics and describes how well a certain material or element is able to transmit electrical current. Your symbol is the Greek symbol for sigma. Occasionally, however, the symbol for gamma from the Greek alphabet is also used. The value of the electrical conductivity is given in sigma per second according to the international system of units.

Which properties enable substances to transmit electricity?

Suitable charge carriers must be present so that electricity can flow through a substance. For example, electrons or ions can be used for this. These must also be able to move freely and be loosely bound. Because only their mobility enables the flow of electricity and the transmission of energy.

What role does temperature play in the electrical conductivity of substances?

The electrical conductivity of a material is temperature dependent. How the temperature affects the conductivity of the respective material depends to a large extent on the structure and the underlying mechanism of charge transfer. In the case of conductors of the first order, i.e. metals that conduct electricity via electrons, the conductivity decreases with increasing temperature. The opposite is true for electrolyte solutions and ion conductors. The rise in temperature increases their electrical conductivity.

How are conductance, resistance and conductivity related to one another?

In electrical engineering, the electrical resistance indicates how high the electrical voltage must be so that a certain current can flow through a conductor. The electrical conductance is a property of a body and a parameter and cannot be equated with electrical conductivity. The unit in which it is specified is Siemens. It can be determined from the reciprocal of the ohmic resistance of a body. The relationship between conductance, resistance and electrical conductivity can be shown as follows. A material or system has a particularly high conductivity if:

  1. the conductance is high
  2. the resistance is at the same time as low as possible

How are the different leaders assigned?

Depending on the strength and possibilities of electrical conductivity, substances are divided into different groups. One distinguishes between:

  • Insulators: These are substances that cannot conduct any significant current. Often these are organic compounds or hydrocarbons. A variety of non-metals also fall into this category.
  • Head: Most metals belong in this group. As a rule, the electrical conductivity is specified at temperatures between 20 and 25 degrees Celsius. The conductivity of the metals silver, copper and gold is particularly high. Manganese has the lowest value among metals.
  • Semiconductors: Their conductivity is between that of conductors and non-conductors. Examples of semiconductors are germanium or silicon. How well they can conduct electricity depends not only on the temperature and the surrounding pressure, but also on the purity of their composition. In the meantime, however, modern processes such as doping have made it possible to increase the conductivity of semiconductors.
  • Superconductors: Certain metals, alloys and ceramics can reach an almost infinite conductivity as soon as a critical temperature is reached. This so-called transition temperature is different for every superconductor. The transition temperature of aluminum is around -271 degrees Celsius. Since it is difficult to maintain such temperatures, superconductors are not used in everyday life. They are used to generate strong magnetic fields. These are required for the operation of particle accelerators or in magnetic resonance tomography.
  • Ionic conductors: Strictly speaking, these are second order conductors. In this case, unlike first-order conductors, the current is passed on via ions. If the ion conductor consists of an electrolyte solution, one no longer speaks of electrical, but of electrolytic conductivity.

Why are metals particularly conductive?

The special conductivity of metals is based on their chemical structure. They usually have one to three valence electrons, also known as external electrons. That means that they are on the outer orbital of the atom. This enables the atoms to form metal bonds with neighboring atoms. This is not possible with ions, however. Since the atomic nuclei of metals only exert a weak force of attraction on their external electrons, these are released more easily and are almost free to move. The loss of the electron creates a metal ion with a positive charge. The mobility of the electrons and the short-term change in charge is the main reason for the good conductivity of metals.

How do you measure electrical conductivity?

The electrical conductivity can only be measured indirectly. Conductometry is a tried and tested method. This is done by allowing electrical current of a known magnitude to flow through the material or system that is to be tested. However, the specific resistance is determined. The electrical conductivity is then calculated from the reciprocal value of the resistance. In liquids, the measurement is carried out with the help of special conductivity measuring devices or conductivity sensors.