Units of measurement 3.1 EXPERT
In the International System, what precisely does Boltzmann's constant measure, the unit of which is joule per kelvin (J/K) ?
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THE CORRECT ANSWER: The link between the thermal energy of a particle and its temperature
The Boltzmann constant (k or kB) is a fundamental physical constant that plays a crucial role in statistical physics. It establishes the bridge between the macroscopic world, that of the temperature that we feel, and the microscopic world, that of the kinetic energy of atoms. In other words, it converts absolute temperature (in kelvins) into energy (in joules).This constant is central to the definition of Boltzmann entropy and is used to calculate the distribution of velocities of molecules in a gas. Since the redefinition of the International System of Units in 2019, the value of the Boltzmann constant is set at exactly 1.380649×10−23 J/K. This historic decision now makes it possible to define the kelvin no longer in relation to the triple point of water, but from an immutable constant of nature, guaranteeing absolute precision in temperature measurements throughout the known universe.