by

Ciro Santilli (@cirosantilli, 34)

Unit of the International System of Units

Table of contents
- Ampere Unit of the International System of Units
  - Ampere in the 2019 redefinition of the SI base units Ampere
- Kilogram Unit of the International System of Units
  - Avogadro project Kilogram
  - Kibble balance Kilogram

Ampere

Unit of electric current.

Affected by the ampere in the 2019 redefinition of the SI base units.

Ampere in the 2019 redefinition of the SI base units

TODO how does basing it on the elementary charge help at all? Can we count individual electrons going through a wire? www.nist.gov/si-redefinition/ampere/ampere-quantum-metrology-triangle by the NIST explains that is it basically due to the following two quantized solid-state physics phenomena/experiments that allows for extremely precise measurements of the elementary charge:

quantum Hall effect, which has discrete resistances of type:
$R_{x y} = \frac{V _{Hall}}{I _{channel}} = \frac{h}{e ^{2} ν}$
(1)
for integer values of $ν$ .
Josephson effect, which provides the Josephson constant which equals:
$K_{J} = \frac{2 e}{h}$
(2)

Kilogram

Unit of mass.

Defined in the 2019 redefinition of the SI base units via the Planck constant. This was possible due to the development of the kibble balance.

Avogadro project

Figure 1. Source.

Kibble balance

Measures weight from a voltage.

www.bipm.org/documents/20126/28432564/working-document-ID-11315/8532173e-8bae-2bdf-b74a-cb48296b4e67

TODO appears to rely on both quantum Hall effect and Josephson effect

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