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Measurements, Christopher Leos Chávez UP190611 Ingeniería Electrónica…

- - - - The ampere is based on a fundamental physical constant: the elementary charge (e), which is the amount of electric charge in a single electron (negative) or proton (positive).
    - - The kelvin has been redefined in terms of the Boltzmann constant, which relates the amount of thermodynamic energy in a substance to its temperature. When the revised SI was approved in November 2018, the new definition became:
        The kelvin, symbol K, is the SI unit of thermodynamic temperature; its magnitude is set by fixing the numerical value of the Boltzmann constant to be equal to exactly 1.380649 × 10-23...J K-1[joules per kelvin].
    - - One mole is the number of atoms in 0.012 kilogram of the most common isotope of elemental carbon (C-12). This is approximately 6.022169 x 10 23 , and is also called the Avogadro constant. But in 2018 he mole is no longer tied to a physical object—the carbon-12 atom. Instead, it is defined purely in terms of the Avogadro constant.
    - - The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.
    - - Specially energized cesium atoms “tick” with a specific frequency. We count 9,192,631,770 of those ticks and call the elapsed time interval a second.
    - - The kilogram was defined in terms of the Planck constant as approved by the General Conference on Weights and Measures (CGPM) on 16 November 2018.
    - - The meter was redefined by international agreement in 1983 as the length of the path traveled by light in a vacuum in 1/299,792,458 of a second. This definition also locked the speed of light at 299,792,458 meters per second in a vacuum.