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Metrological Traceability - Redefined SI Unit

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INTRODUCTION The SI (International System of Units) underwent a significant redefinition in 2019. One of the most notable changes was the redefinition of four base units: the kilogram, the ampere, the kelvin, and the mole. These redefinitions were based on fundamental constants of nature, providing more stable and precise definitions for these units.   The  transition frequency of the  caesium-133 atom Δν Cs   is   9 192 631 770 Hz 9 192 631 770 Hz The speed of light in vacuum   c   is   299 792 458 m/s 299 792 458 m/s The Planck constant   h   is   6.626 070 15 x 10 –34  J s 6.626 070 15 x 10 –34  J s The elementary charge   e   is   1.602 176 634 x 10 –19  C 1.602 176 634 x 10 –19  C The Boltzmann constant   k   is   1.380 649 x 10 –23  J/K 1.380 649 x 10 –23  J/K The Avogadro constant   N A   is   6.022 140 76 x 10 23  mol –1 6.022 140 76 x 10 23 ...
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Calibration - Preparation of ICE Point (Overview)

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Preparing the ice point is crucial for calibrating thermometers accurately. While there might not be a specific "international guideline" for preparing the ice point, there are generally accepted best practices followed by calibration laboratories and industries worldwide. Here's how to prepare the ice point: Equipment and Materials Needed: Distilled water Crushed or shaved ice Clean container (such as a Dewar flask or a thermos) Stirring rod Thermometers to be calibrated Thermometer with known accuracy (primary thermometer) Timer or stopwatch Procedure: Cleanliness Precautions: Ensure that all equipment, containers, and thermometers are clean and free of contaminants. Any impurities can affect the accuracy of the calibration process. Prepare Distilled Water: Use distilled water to minimise impurities that could affect the ice point temperature. Prepare Ice: Crush or shave ice into small pieces. The ice should be free of impurities and air bubbles. Prepare the Container:...
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