Capacity normal

The capacity standard is an electrical capacitor with a well-defined capacity . It is set by metrologists for standardization.

A capacity standard is determined, for example, by the Physikalisch-Technische Bundesanstalt (PTB) on the basis of the elementary charge of electrons . By means of devices that count individual electrons, a capacitor with an approximate capacity of 1  picofarad is charged with the charge (typically 10 ⁷ electrons, multiplied by their respective charge, the elementary charge). The devices are based, for example, on single electron transistors . ${\displaystyle Q}$

By measuring the voltage applied to the capacitor , the capacitance is determined with much less measurement inaccuracy as: ${\displaystyle U}$ ${\displaystyle C}$

${\displaystyle C={\frac {Q}{U}}}$

Web links

• 10 million electrons as capacity standard. In: ptb.de. Physikalisch-Technische Bundesanstalt, accessed on January 21, 2018 .