Metre and kilogram Metric system

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one litre equivalent volume of cube edges of 10 cm , kilogram designed 1 litre of water @ melting point of ice.


the available technology of 1790s made impracticable use these definitions basis of kilogram , metre, prototypes represented these quantities insofar practicable manufactured. on 22 june 1799 these prototypes adopted definitive reference pieces, deposited in archives nationales , became known mètre des archives , kilogramme des archives. copies made , distributed around france. these artefacts replaced in 1889 new prototypes manufactured under international supervision. insofar possible, new prototypes exact copies of original prototypes, used later technology ensure better stability. 1 of each of kilogram , metre prototypes chosen lot serve definitive international reference piece remainder being distributed signatories of metre convention.


in 1889 there no accepted theory regarding nature of light 1960 wavelength of specific light spectra give more accurate , reproducible value prototype metre. in year prototype metre replaced formal definition defines metre in terms of wavelength of specified light spectra. 1983 accepted speed of light in vacuum constant , constant provided more reproducible procedure measuring length. therefore, metre redefined in terms of speed of light. these definitions give better reproducibility , allow anyone, anywhere suitably equipped laboratory, make standard metre.








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