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It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10 12 Hz, K cd, to be 683 when expressed in the unit lm W −1, which is equal to cd sr W −1, or cd sr kg −1 m −2 s 3, where the kilogram, metre and second are defined in terms of h, c and ∆ν Cs."
In the natural sciences, a vector quantity (also known as a vector physical quantity, physical vector, or simply vector) is a vector-valued physical quantity. [9] [10] It is typically formulated as the product of a unit of measurement and a vector numerical value (), often a Euclidean vector with magnitude and direction.
The kelvin is defined by setting the fixed numerical value of the Boltzmann constant k to 1.380 649 × 10 −23 J⋅K −1, (J = kg⋅m 2 ⋅s −2), given the definition of the kilogram, the metre, and the second. mole: mol amount of substance: The amount of substance of 6.022 140 76 × 10 23 elementary entities.