Units and Constants
The following are the set units for the International System (Syst�me Internationale or SI) of units and a list of common constants.
| Basic SI Units: | ||
| Physical Quantity | Name of Unit | Symbol |
| length | meter | m |
| mass | kilogram | kg |
| time | second | s |
| electric current | ampere | A |
| thermodynamic temperature | Kelvin | K |
| luminous intensity | candela | cd |
| Supplementary SI Units: (Dimensionless) | ||
| plane angle | radian | rad |
| solid angle | steradian | sr |
| Derived SI Units: | |||
| Physical quantity | Name of Unit | Symbol | Definition |
| energy | joule | J | kg m2 s-2 = N m |
| force | newton | N | kg m s-2 = J m-1 |
| power | watt | W | kg m2 s-3 = J m-1 |
| electric charge | coulomb | C | A s |
| electric potential difference | volt | V | kg m2 s-3 A-1 = J A-1 s-1 |
| electric resistance | ohm | W | kg m2 s-3 A-2 = V A-1 |
| electric capacitance | farad | F | A2 s4 kg-1 m-2 = A s V-1 |
| magnetic flux | weber | Wb | kg m2 s-2 A-1 = V s |
| inductance | henry | H | kg m2 s-2 A-2 = V s A-1 |
| magnetic flux density | tesla | T | kg s-2 A-1 = V s m-1 |
| luminous flux | lumen | lm | cd sr |
| illumination | lux | lx | cd sr m-2 |
| frequency | hertz | Hz | cycle per second |
| customary temperature | degrees Celsius | ºC | ºC = K - 273.15 |
| Other Derived SI Units: | ||
| Physical quantity | Unit | Symbol |
| area | square meter | m2 |
| volume | cubic meter | m3 |
| density | kilogram per cubic meter | kg m-3 |
| velocity | meter per second | m s-1 |
| angular velocity | radian per second | rad s-1 |
| acceleration | meter per second squared | m s-2 |
| pressure | newton per square meter | N m-2 |
| kinematic viscosity, diffusion coefficient |
square meter per second | m2 s-1 |
| dynamic diffusion | newton second per square meter | N s m-2 |
| electric field strength | volt per meter | V m-1 |
| magnetic field strength | ampere per meter | A m-1 |
| luminance | candela per square meter | cd m-2 |
| radioactivity | curie | Ci = 3.7 x 1010 s-1 |
| Common Constants: | ||
| Quantity | Symbol | Value |
| atomic mass unit | u | 1.660 540 2(10) x 10-27 kg |
| Avogadro's Number | NA | 6.022 136 7(36) x 1023 |
| Bohr magneton | mB | 9.0274 015 4(31) x 10-24 J T-1 |
| Bohr radius | a0 | 0.529 177 249(24) x 10-10 m |
| Boltzmann's constant | k | 1.380 658(12) x 10-23 J K-1 |
| Compton wavelength | lC | 2.426 310 58(22) x 10-12 m |
| Electron mass | me | 9.109 389 7(54) x 10-31 kg |
| Electron-volt | eV | 1.602 177 33(49) x 10-19 J |
| Elementary charge | e | 1.602 177 33(49) x 10-19 C |
| Gas constant | R | 8.314 510(70) J K-1 mol-1 |
| Gravitational constant | G | 6.672 59(85) x 10-11 N m2 kg-2 |
| Hydrogen ground state | E0 | 13.605 698(4) eV |
| Magnetic flux quantum | F0 | 2.067 834 61(61) x 10-15 Wb |
| Neutron mass | mn | 1.674 928 6(10) x 10-27 kg |
| Nuclear magneton | mn | 5.050 786 6(17) x 10-27 J T-1 |
| Permeability of free space | m0 | 4p x 10-7 N A-2 |
| Permittivity of free space | e0 | 8.854 187 817 x 10-12 C2 N-1 m-2 |
| Planck's constant | h | 6.626 075(40) x 10-34 J s |
| Proton mass | mp | 1.672 623(10) x 10-27 kg |
| Quantized Hall resistance | 25 812.805 6(12) W | |
| Rydberg constant | RH | 1.097 373 153 4(13) x 107 m-1 |
| Speed of light in vacuum | c | 2.997 924 58 x 108 m s-1 |
| SI Prefixes | ||
| Prefix | Abbreviation | Power |
| yotta | Y | 1024 |
| zetta | Z | 1021 |
| exa | E | 1018 |
| peta | P | 1015 |
| tera | T | 1012 |
| giga | G | 109 |
| mega | M | 106 |
| kilo | k | 103 |
| hecto | h | 102 |
| deka | da | 101 |
| deci | d | 10-1 |
| centi | c | 10-2 |
| milli | m | 10-3 |
| micro | m | 10-6 |
| nano | n | 10-9 |
| pico | p | 10-12 |
| femto | f | 10-15 |
| atto | a | 10-18 |
| zepto | z | 10-21 |
| yocto | y | 10-24 |