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posted by martyb on Wednesday June 21 2017, @04:20AM   Printer-friendly
from the worth-the-weight^Wwait dept.

Technische Universität Ilmenau and the Physikalisch-Technische Bundesanstalt (the National Metrology Institute of Germany) are developing a balance which is required for measuring the redefined kilogram that will be introduced in 2018. Called the Planck balance, this highly precise electronic weighing balance is not based on weights, but refers to the fundamental physical constant called Planck's constant. The balance will be used worldwide for calibrating other scales or balances so that they correspond to the system with this new method. The new balance will also be used in industry for measuring weights.

In many sectors, there is a significant demand for highly precise balances, including pharmaceutical companies for precise dosing of medical products, in official metrology service labs for calibrating scales for food, and in police departments, for the proof of toxic substances and in ballistics.

The original kilogram, a 4 cm cylinder made from platinum and iridium and stored under three glass domes in a safe near Paris since 1889, is becoming lighter. Over 100 years, it has lost 50 millionths of a gram. As all scales worldwide refer indirectly to this unique kilogram, they all weigh incorrectly, even if by minimal and negligible amounts. Although the original kilogram is becoming lighter, structurally identical copies of the prototype are used worldwide – which means that these copies are slowly becoming heavier relative to the prototype. Therefore, a new standard is required that does not change and cannot be damaged or lost.

In 2018, the new kilogram will be adopted at the 26th General Conference on Weights and Measures. It is not defined by an object or a physical mass, but by Planck's constant. The highly precise, continuously measuring Planck balance, developed by the German university Technische Universität Ilmenau, operates on the principle of electromagnetic force compensation. Simply put, a weight on one side is to be balanced by electrical force on the other. This electrical force is inextricably linked with the Planck's constant and can be directly referred to the new kilogram definition. As this balance is the first self-calibrating instrument of its kind, masses determined as reference or standard masses for calibrating scales and balances are no longer required. Another advantage of the Planck balance is its wide measuring range, from milligrams to one kilogram. At the end of the year, the first prototype of the balance will be available and ready for use.

At last, a balanced article.


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  • (Score: 0) by Anonymous Coward on Wednesday June 21 2017, @12:27PM (1 child)

    by Anonymous Coward on Wednesday June 21 2017, @12:27PM (#528973)

    I think the Watt balance has been renamed Planck balance to keep the Germans happy. They have historically supported replacing the kg artifact with a Silicon sphere that has a known number of atoms.

  • (Score: 2) by stormwyrm on Wednesday June 21 2017, @11:15PM

    by stormwyrm (717) on Wednesday June 21 2017, @11:15PM (#529260) Journal
    The only proposal to rename the watt balance I know of is to call it the Kibble balance, after its inventor Bryan Kibble.
    --
    Numquam ponenda est pluralitas sine necessitate.