Question: World’s standard definition of Kilogram, Second & Metre was redefined recently on which of the following physical constants?
(a)Gravitational Constant
(b)Planck’s Constant
(c)Richardson constant
(d)Stefan-Boltzmann constant
Answer: (b)
Related facts:
- During November 13th-16th 2018; the 26th meeting of the General Conference on Weights and Measures (CGPM) was held at Palais des Congrés, Versailles, France.
- This meeting was very special and historic as the members have voted for the redefinition of 130 years old “Le grand K – the SI unit of kg” in terms of the fundamental Planck’s constant (h). The new definitions will come into force on 20th May 2019.
- The definition of the seven base units namely, second, metre, kilogram, ampere, Kelvin, mole and candela has been changed from being linked to artefacts to being based on the fundamental constants on nature.
- It is to be noted that CGPM is the highest international body of the world for accurate and precise measurements. The CGPM comprises 60 countries including India and 42 Associate Members. India is also a member.
- The metric system was intended to be rational; universal set of units “for all people, for all time”. The SI unit will finally be truly universal system, free of any human artefacts.
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