The Physics
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Opus in profectus

International System of Units

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Summary

The seven defining constants of the International System
description symbol value
hyperfine transition of a cesium atom ΔνCs 9,192,631,770 Hz
speed of light c 299,792,458 m/s
Planck's constant h 6.62607015 × 10−34 J s
charge on a proton e 1.602176634 × 10−19 C
Boltzmann's constant k 1.380649 × 10−23 J/K
Avogadro's constant NA 6.02214076 × 1023 1/mol
luminous efficacy of green light Kcd 683 lm/W
The seven base units of the International System
quantity unit symbol
length meter m
mass kilogram kg
time second s
electric current ampère A
temp­erature kelvin K
amount of substance mole  mol 
luminous intensity candela cd
Divisions of the International System
factor prefix symbol
10−1 deci d
10−2 centi c
10−3 milli m
10−6 micro µ
10−9 nano n
10−12 pico p
10−15 femto f
10−18 atto a
10−21 zepto z
10−24 yocto y
10−27 ronto r
10−30 quecto q
Multiples of the International System
factor prefix symbol
101 deca da
102 hecto h
103 kilo k
106 mega M
109 giga G
1012 tera T
1015 peta P
1018 exa E
1021 zetta Z
1024 yotta Y
1027 ronna R
1030 quetta Q