[SI Illustration.png](https://upload.wikimedia.org/wikipedia/commons/2/2e/SI_Illustration.png)
I know mol and vaguely remember the Avogadro-constant N(A). I guess the correlation between m and c points to E=mc^2. What are the other symbols and correlations referring to?
In: Physics
Metric units are defined in terms of physical constants.
The inner circle represent which constant is used for each unit:
* The Kilogram is defined in term of the plank constant h
* The Meter is defined in term of the speed of light c
* The Second is defined in term of the frequency of Caesium-133 hyperfine transition Δν
* The Ampere is define in term of the elementary charge e
* The Kelvin is defined in term of the Boltzmann constant k
* The mol is defined in term of the Avogadro constant Na
* The Candela is defined in term of the luminous efficacy of a radiation of frequency Kcd
The m in E=mc² is mass not meter. This equation states that erngy and mass are linked, but isn’t used to define the unit of energy (the Joule), as there exists much simpler ways to derive energy without invoking relativity.
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