From UPSC perspective, the following things are important :
Prelims level : Kibble Balance, Kilogram and its definiton
Mains level : Not Much
The prototype of one kilogram (NPK-57) is now available in India and placed at the National Physical Laboratory, New Delhi. The new definition of kilogram which has come into effect from May 2019 and few countries have developed the system of realization of unit of mass ‘kg’.
How much is a kilogram?
- Over the centuries, it has been defined and redefined, with a standard in place since 1889.
- Called Le Grand K, a cylinder of platinum-iridium is locked up in a jar at the International Bureau of Weights and Measures (BIPM) in Paris.
- For nearly 130 years, the mass of this cylinder has been the international standard for the kilogram.
Redefining what constitutes 1 Kg
- Representatives from 57 countries will vote in Versailles, France, to redefine SI, or the International System of Units.
- The kilogram’s definition will be based on a concept of physics called the Planck constant.
- Reports worldwide suggest that the new definition is set to be voted in.
Using a Kibble Balance
- Kibble balance is a self-calibrating electromechanical balance and provides the measurements of mass, traceable in terms of electrical parameters and provides linkage of macroscopic mass to the Planck constant (h).
- The advantages of Kibble balance would be that the NPK need not to be sent to BIPM for calibrations and the accuracy and stability of Kibble balance is very high.
- This is very important where low weights with high accuracies are essential, for example in pharmaceuticals and biotechnologies.