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Milli (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth (10 −3). [1] Proposed in 1793, [2] and adopted in 1795, the prefix comes from the Latin mille, meaning one thousand (the Latin plural is milia). Since 1960, the prefix is part of the International System of Units (SI).
The prefix symbols are always prepended to the symbol for the unit without any intervening space or punctuation. [9] This distinguishes a prefixed unit symbol from the product of unit symbols, for which a space or mid-height dot as separator is required. So, for instance, while 'ms' means millisecond, 'm s' or 'm·s' means metre-second.
A unit prefix is a specifier or mnemonic that is added to the beginning of a unit of measurement to indicate multiples or fractions of the units. Units of various sizes are commonly formed by the use of such prefixes. The prefixes of the metric system, such as kilo and milli, represent multiplication by positive or negative powers of ten.
The original is a unit of energy, equal to the energy in one mole (1 mol) of photons. The second is a unit of amount of photons, equal to one mole (1 mol) of photons. The rayleigh (R) is a unit of photon flux rate density equal to 10 10 m −2 ⋅s −1 (10 4 mm −2 ⋅s −1).
The gram is the base unit of mass instead of the kilogram, ... since it can be defined in terms of the Avogadro number, ... milli m 0.001 10 −3: micro u 0.000 001: ...
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.
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. K: SI: Physics: Basic: mole: mol: N: amount of substance: The amount of substance of exactly 6.022 140 76 × 10 23 elementary entities.
Find facts relating the original unit to the desired unit: 1 mile = 5280 feet and 1 hour = 3600 seconds; Next use the above equations to construct a fraction that has a value of unity and that contains units such that, when it is multiplied with the original physical value, will cancel the original units: