The kilogram has changed forever. Here’s why.

The SI system of units have been revamped recently.

Instead of being based on 7 base units, it is now based on 7 physical constants. Don’t worry. The magnitude of the 7 base units (kg, m , s, etc) are not affected. It’s only the way they are defined that have been changed.

The seven defining constants are:

  • the caesium hyperfine frequency ΔνCs
  • the speed of light in vacuum c
  • the Planck constant h
  • the elementary charge e
  • the Boltzmann constant k
  • the Avogadro constant NA, and
  • the luminous efficacy of a defined visible radiation Kcd

Watch the following video if you’re interested to know the rational for the change.

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