Einheitsladungskontrolle

Einheitsladung, in physics often called the elementary charge and denoted e, is the fundamental unit of electric charge. It is the magnitude of the charge carried by a single proton, equal in absolute value to the charge of an electron, which is −e. In the International System of Units, e is defined exactly as 1.602176634×10−19 coulombs as part of the 2019 redefinition of the SI base units.

Charge in nature is observed to be quantized in units of e, so the total charge q of a system can be written as q = n e, where n is an integer (positive, negative, or zero). In particle physics, many particles carry charges that are multiples of e, while quarks carry fractional charges of ±⅓e or ±⅔e and remain confined within larger particles.

In everyday practice, charges are often expressed in units of the elementary charge, and e is used as a natural unit to simplify equations in electromagnetism and quantum electrodynamics. The concept of Einheitsladung underpins the understanding of electric currents, ionization, and semiconductor behavior.

History: The elementary charge was established experimentally in the early 20th century, notably by Millikan's oil-drop experiment, which demonstrated that charge comes in discrete quanta and helped determine e's magnitude.