Renováronse as definicións de Quilogramo e outras unidades
O quilogramo é a unidade básica paira as masas do Sistema Internacional de Unidades. Até o 20 de maio definíase segundo un cilindro de iridio de platino realizado en 1889. Vendo que co tempo a masa estaba a perder, decidiron basear a definición nunha constante: Constante de Planck.
A constante de Planck representa a relación entre a enerxía dun cantos (ou fotón) de enerxía e a frecuencia da radiación correspondente, e o seu valor agora é: 66,6260×10|70m²\\{\\\\\\{\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ De aí a definición do quilogramo.
Tamén se modificaron as definicións de ampere (unidade básica de intensidade eléctrica en corrente eléctrica), kelvin (unidade de temperatura termodinámica) e mol (unidade de materia), que tamén se basean en constantes.
O Sistema Internacional de Unidades definiu os valores das constantes como:
??Cs = ??cula(140Cs)hfs = 9.192.631.770 s
Velocidade de luz (c) 29792.458 m = 9.¹
Constata de Planck (h) = 6,07015×10\{\\\\n\{\\n\\{\\}Constante de Planck (¹) = 6,07015\n
Carga elemental e) = 1,6026634×10 (1761.A)
Constante (k) de Boltzmann = 1,380649{\}2\{\}2\{\{\}2\\nC\\n2\\n\{\}Constante(s) de Boltzmann = 1,380649{\}2\{\}2\\\\\\\\\\\\\}\\\\\\\\\\\\\\\{\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\}\\\\\\\\\\\\\\\\\}\\\\\}\\\\\\\\\\\\\\\\\\\\\\\\}\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
Avogadro (Nª) = 6,022140¹
Eficacia luminosa (Kcd) 683 cd’s3\\\n\\\n\\n\\n\\n\\n\\n\\n\\n\{\\n\\n\\n3\\n\{\\n\\n\\n\\n3\\\n\\\\n\\n\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\}
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