Elementary charge

The elementary charge (symbol ) is the smallest amount of electric charge existing freely. The charge of free particles and quantities of matter is either zero or an integer ( positive or negative ) multiple of. To have, for example electron and muon the charge of a proton and a positron having the charge. Although the quarks of the Standard Model have loads of or not, but do not come as free particles. See the Confinementphänomen the quarks.

The elementary charge is a fundamental constant. Their value is

With an uncertainty of Coulomb.

The value of the elementary charge is decisive for the strength of the electromagnetic interaction, see fine structure constant.

The fact that the charge has a fixed smallest unit that has been suggested in the 19th century due to electrochemical reactions. Was precisely determines the size of the elementary charge for the first time by the physicist Robert Andrews Millikan oil drop experiment with the named after him. Among other things, this work Millikan was awarded the Nobel Prize in 1923. Modern regulations of the fine structure constant and thus the elementary charge use, for example, the quantum Hall effect.

Work is underway to define the SI unit of amount of charge as a multiple of the elementary charge,

See Avogadro project.

Conjunction with other sizes

By multiplying the unit charge with the Avogadro constant results in the Faraday constant, which plays a role in the electrochemistry.

In particle energies of particles frequently in the unit electron volt (eV ) are given. An electric voltage, the energy (e.g., one electron ) receives an elementary charge when passing through an acceleration voltage of 1 volt. It is the translation: