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Friday, October 27

The Kilogram set to get new measure in 2019.

 TNPSC Current Affairs - October 2017 by TNPSC Guru
Since 1875 Kilogram is defined as the mass of a metal cylinder (made of 90% platinum and 10% iridium) in a locked vault in basement of the Bureau International des Poids et Mesures (BIPM), Paris. The cylinder is known as Le Grande K and officially as “the International Prototype Kilogram,” or IPK

The scientist from around the world made a careful measurement and found that their masses are diverging for around 50 micrograms or 50 parts per million. Having a standard of mass that changes is unacceptable. The kilogram is the last of the base SI Units is still be defined by a physical object.

In 2011, The General conference on weights and measures decided to redefine the kilogram based on Planck’s constant.

It doesn’t mean that old Avogadro approach is useless , we can use Avogadro approach to calculate Planck’s constant and vice versa. So here both way of approach has to be used to redefine the kilogram

About new Method.
  • Watt balance or kibble balance will place the mass in the left side where mass pan is attached to a coil of wire in a magnetic field and the right side is a motor and then the apparatus should be sealed and operated in vacuum
  • The balance operates in 2 modes, weighting mode and velocity mode, both are required to determine Planck’s constant .
  • Using this method we can measure the accurate Kilogram

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