One step closer to a new kilogram

R&D Mag – The National Physical Laboratory (NPL) has produced technology capable of accurate measurements of Planck’s constant, which is a significant step towards changing the international definition of the kilogram—currently based on a lump of platinum-iridium metal kept in Paris, France.

Planck’s constant is a fundamental constant of nature which relates the frequency (color) of a particle of light (a photon) to its energy. By using two quantum mechanical effects discovered in the last 60 years: The Josephson effect and the quantum Hall effect, electrical power can be measured in terms of Planck’s constant (and time).

A Planck-based kilogram would mean a universal standard that could be replicated anywhere in the world at any time. more>


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