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Base SI units

Basic Physical QuantitySI UnitSymbol
length metre m
mass kilogram kg
time second s
electric current ampere A
thermodynamic temperature kelvin K
amount of substance mole mol
luminous intensity candela cd

Supplementary units

                                               SI Unit
Symbol
plane angle  radian rad
solid angle steradian sr

Some derived SI units with special names

Physical QuantitySI UnitSymbol
frequency  hertz Hz
energy joule J
force newton N
power watt W
electric charge coulomb    C
potential difference                     volt V
resistance ohm
capacitance farad F
conductance siemens   S
magnetic flux weber Wb
inductance henry H
magnetic flux density tesla T
luminous flux lumen lm
illumination lux lx

Prefixes for SI units

FractionPrefixSymbolMultiplePrefixSymbol
10-1 deci d 10 deka da
10-2 centi c 102 hecto h
10-3 milli m 103 kilo k
10-6 micro μ 106 mega M
10-9 nano n 109 giga G
10-12 pico p 1012 tera T
10-15 femto f 1015 peta P
10-18 atto a 1018 exa E