On Friday, representatives from 60 countries have approved a new definition of the kilogram — which is equal and must be calculated as the basic unit of mass.
Although this will not affect our daily lives, the significance of this step for the scientific world and industry, which requires extremely accurate measurements cannot be overemphasized.
Kilogram — one of the seven base units of the international system of measurements (SI).
Determine four of them — the kilogram and ampere (a measure of the strength of the current), Kelvin (temperature), and mole (amount of substance) — was revised by the General conference of weights and measures, which passes near Paris, in Versailles.
It should be noted. that kilogram is the last of the SI units, was based on a real physical object. Taken in 1901, the official definition of exactly what was “the Kilogram is a unit of mass equal to the mass of the international prototype of the kilogram”.
The international prototype is a 4-inch cylinder consisting of 90% platinum and 10% iridium. It was produced in London and from 1889 stored by the International Bureau of weights and measures in the city of sèvres near Paris.
But physical objects can lose atoms (actually steaming) or, alternatively, to absorb molecules from the surrounding air, so over the past century, the mass standard was changed to a few tens of micrograms.
This means that all the other prototypes of the kilogram, which is calibrated scale around the world, strictly speaking, was not perfectly accurate. Although such small deviations can present a huge problem for precise scientific calculations. How to calculate kilos
The vote Friday was formal: intense debate has already taken place (several countries have proposed their own, alternative definition), the decision was agreed in advance.
Now kg is supposed to be measured by the so-called Watt scales (or balance of the Kibble) — this instrument determines the mass via Planck’s constant, the basic constant of quantum theory.
Simply put, the definition of the kilogram linked to the amount of electromagnetic energy required to balance the object of the relevant mass. Master kettlebell replaces an electric current and a voltage proportional to the force generated her gravitational field.
These values, unlike the physical object can not be modified or abyss. And in addition, to accurately measure the pounds now can any scientists around the world, not just those who have access to the original Paris weight or her copy.
A new definition of the kilogram should enter into force in may next year.
On Friday also revised the definition of the ampere, Kelvin and mole.
Amps (amperage) are measured by counting the number generating the current, and one of transmitted electrons.
Kelvin (temperature) — due to the acoustic thermometry, measuring the speed of sound in a sphere filled with gas of a certain temperature.
Mole (amount of substance) reviewed by using a tool that determines the exact number of atoms in a perfect sphere of pure silicon-28.
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