SP.304a-2017 org/10.6028/NIST. from: is free ofcharge This publication www.nist.gov/metric [email protected] July 2017 NIST SP304A Measurement League counterparts. The SI,commonly known asthemetric system, iseasy to use. The International System ofUnits(SI) ismade upof7baseunits,featured onthischartwiththeir 1/683 watt per steradian. intensity inthat direction of hertz andthat hasaradiant of frequency 540x10 monochromatic radiation of asource that emits intensity, inagiven direction, The candelaistheluminous LUMINOUS INTENSITY CANDELA ( https://doi. of 1/299 vacuum duringatimeinterval the path traveled by light in The meter isthelengthof METER (

7 92 92 4 58 prototype ofthekilogram (IPK). equal to themass oftheinternational The kilogram istheunitofmass, KILOGRAM ( cd m ofasecond. ) LENGTH )

10 YZ SI symbols are thesame worldwide, regardless ofthe spelling, language, 12 2 yotta 4 1 000 000 000 000 000 000 000 000

or alphabet. Prefix symbols are usedwithaunit symbol to represent 10 2

zetta 1 1 000 000 000 000 000 000 000 10 EP 18

exa 1 000 000 000 000 000 000 state ofthecesium 133atom. the two hyperfine levels oftheground corresponding to the transition between 9 192 631 770 periodsoftheradiation The second istheduration of SECOND ( smaller or larger unitsby factors that are powers of 10.

kg 10

peta 15 1 000 000 000 000 000 ) 10 TG

12 tera 1 000 000 000 000 MASS 10

giga 9 1 000 000 000 10 s Mk ) TIME mega 6 1 000 000

10

kilo 3 1 000 PREFIXES

10 hd

hecto 2 100

10 ad deka 1 10 10

0 1 10

deci -1 0.1 10 c point ofwater. thermodynamic temperature ofthetriple temperature, isthefraction 1/2 The kelvin, unitofthermodynamic KELVIN (K)TEMPERATURE centi -2 0.01 10 m

milli -3 0.001

10 G µ micro -6 0.000 001 U A

R

D 10

I np A -9 atoms in0.012 kilogram ofcarbon12. elementary entities asthere are of asystem whichcontains asmany The moleistheamount ofsubstance AMOUNT OFSUBSTANCE MOLE (

nano 0.000 000 001 N

S

10 O F

-1

pico 0.000 000 000 001 T 2

H E

10

S fa

femto -1 0.000 000 000 000 001 I 5 10 mol

atto -1 0.000 000 000 000 000 001 8 length. 2 x10 conductors aforce equalto produce between these apart invacuum, would section, andplaced 1meter of negligiblecircular cross conductors ofinfinite length, in two straight parallel current which,ifmaintained The ampere isthat constant ELECTRIC CURRENT AMPERE 10 zy zepto -2 0.000 000 000 000 000 000 001 1 )

10 -7 yocto -2 0.000 000 000 000 000 000 000 001 4 73.

newton permeter of 16 ofthe

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