SI .UNIT TABLE

SI Units  Math Symbol and compound formula S I Unit formula SI unit-table State -and-capital loss and profit Table I. Basic Units Quantity Unit Symbol Definition Length  meter  m  1983, 17th CGPM:  The path travelled by light in vacuum during a time interval of 1/299792458 seconds. This fixes the speed of light to exactly 299792458 m/s. Mass  kilogram  kg  1901, 3rd CGPM:  Mass of the platinum-iridium prototype at BIPM in Sevres. Time  second  s  1968, 13th CGPM:  One second equals 9192631770 periods of the radiation due to the transition between the two hyperfine levels of the ground state of Cesium 133. Electric current  ampere  A  1948, 9th CGPM:  Given two parallel, rectilinear conductors of negligible circular cross-section positioned 1 m apart in vacuum, one ampere is the electric current which, passing through both of them, makes them attract each other by the force of 2.10-7 newtons per every meter of length. This fixes the permeability of vacuum to exactly 2π*10-7 H/m. Temperature  kelvin  K  1968, 13th CGPM:  One degree K equals 1/273.16 of the thermodynamic temperature of the triple point of water. Quantity of substance  mole  mol  1971, 14th CGPM:  The amount of a substance composed of as many specified elementary units (molecules, atoms) as there are atoms in 0.012 kg of Carbon 12. Luminosity  candle  cd  1979, 16th CGPM:  The candle (or candela) is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540.1012 hertz and that has a radiant intensity in that direction of 1/683 W/sr. Table II. Derived units with assigned names Quantity Unit Symbol Equals Definition / Note Space and time: Plane angle  radian  rad  The plane angle which,  when centered in a circle, cuts off an arc whose length is equal to the circle radius. Solid angle  steradian  sr  The solid angle which,  when centered in a sphere, cuts off a cap whose surface equals that of a square having the radius as side. Frequency  hertz  Hz  1 s-1 [number of events or cycles]/[time].  Mechanics: Force  newton  N  1 kg.m.s-2 [mass].[acceleration].  Pressure  pascal  Pa  1 N.m-2 [force]/[area]. Also: stress.  Energy  joule  J  1 N.m  [force].[length]. Also: Work, Heat  Power  watt  W  1 J.s-1 [energy]/[time]. Also: Radiant flux  Thermodynamics: Temperature  celsius  oC  1 K  T [oC] = T [K] -273.15 (the offset is exact!).  Electromagnetism: Charge  coulomb  C  1 A.s  [current].[time].  Potential  volt  V  1 W.A-1 [power]/[current]. Only differences are measurable!  Resistance  ohm  Ω  1 V.A-1 [Δpotential]/[current].  Conductance  siemens  S  1 A.V-1 [current]/[Δpotential].  Capacitance  farad  F  1 C.V-1 [charge]/[Δpotential].  Inductance  henry  H  1 V.s.A-1 [Δpotential]/[rate of change of current].  Magnetic flux  weber  Wb  1 J.A-1 [energy]/[current].  Magnetic flux density  tesla  T  1 Wb.m-2 [magnetic flux]/[area]. Also magnetic induction.  Optics: Luminous flux  lumen  lm  1 cd.sr  [luminosity].[solid angle].  Illuminance  lux  lx  1 lm.m-2 [luminous flux]/[area].  Convergence  dioptry  dioptry  1 m-1 Inverse of focal length.  Radioactivity and radiation: Activity  becquerel  Bq  1 s-1 [number of decay events]/[time].  Absorbed dose  gray  Gy  1 J.kg-1 [energy]/[mass].  Dose equivalent  sievert  Sv  1 J.kg-1 [energy]/[mass]. Absorbed dose re-normalized by biological effects.  Chemistry: Katalytic activity  katal  kat  1 mol.s-1 [quantity of substance]/[time].  Table III a. SI Units prefixes Prefix Symbol Factor Examples of usage Origin Yotta  Y  1024 0.2 YW, 1.23Y [W]  Greek 'octo' (eight, 10008) Zetta  Z  1021 3.33 Zs, 3.33Z [s]  French 'sept' (seven, 10007) Exa  E  1018 1.23 Ekg, 1.23E [kg]  Greek 'six' (10006) Peta  P  1015 7.5 Ps, 7.5P [s]  Greek 'five' (10005) Tera  T  1012 0.5 Tm, 0.5T [m]  Greek 'teras' = monster  Giga  G  109 1.2 GΩ, 1.2G [Ω]  Greek 'gigas' = giant  Mega  M  106 7 MW, 7M [W]  Greek 'megas' = large  Kilo  K, k  103 33 km, 33K [m]  Greek 'kilioi' = thousand  hecto  h  100  Deprecated by SI  Greek 'hekaton' = hundred  deca  da  10  Deprecated by SI  Greek 'deka' = ten  deci  d  0.1  Deprecated by SI  Latin 'decima pars' = one tenth  centi  c  0.01  Deprecated by SI  Latin 'centesima pars' = one hundredth  milli  m, k  10-3 22 mm , 1.2m [m]  Latin 'millesima pars' = one thousandth  micro  µ, u  10-6 2.7 uJ , 2.7µ [J]  Greek 'mikros' = small  nano  n  10-9 2.2 nF, 2.2n [F]  Latin 'nanus' = dwarf  pico  p  10-12 1.5 pA, 1.5p [A]  Spanish 'pico' = minimal measure  femto  f  10-15 4.8 fs, 4.8f [s]  Danish and Norvegian 'femten' = fifteen (10-15) atto  a  10-18 1.2 ag, 1.2a [g]  Danish and Norvegian 'atten' = eighteen (10-18) zepto  z  10-21 0.2 zm, 1.2z [m]  French 'sept' (seven, 1000-7) yocto  y  10-24 1 ys, 1y [s]  Greek 'octo' (eight, 1000-8) Table III b. Binary prefixes for Bytes which are not a part of SI  Prefix Symbol Factor Value Examples Kilo  KB  210 1024  12345 KB = 12 641 280 bytes  Mega  MB  220 1 048 576  420 MB fits in my PC's dynamic RAM  Giga  GB  230 1 073 741 824  16 GB flash-memory pen drive costs $20  Tera  TB  240 1 099 511 627 776  3.9 TB hard disks are a reality  Peta  PB  250 1 125 899 906 842 624  13.5 PB is the CIA total memory capacity  Exa  EB  260 1 152 921 504 606 846 976  1 EB is still a bit out of reach (AD 2010)  Zetta  ZB  270 1 180 591 620 717 411 303 424  How many ZB to hard-copy a human being ???  Yotta  YB  280 1 208 925 819 614 629 174 706 176  1 YYB is still nothing compared with the Universe  Table IV. Accepted non-SI units compiled according to the US Federal Register (ref.4). Unit of Symbol Equals Definition / Note Degree of arc  plane angle  o (π/180) rad  Minute of arc  plane angle  '  (1/60) o Second of arc  plane angle  "  (1/60)'  Minute  time  min  60 s  Hour  time  h  60 min  Day  time  d  24 h  Notice that the duration of a day is not linked to Earth motion!  Liter  volume  L, l  0.001 m3 Often used sub-units are deciliter (dl) and centiliter.(cl).  Gram  mass  g  0.001 kg  A tolerated anomaly: the basic unit of mass (kg) has a prefix.  Ton  mass  t  1000 kg  More precise term: metric ton.  Bit  information  bit  -  The smallest, dimensionless quantum of information  Baud rate  info flux  Baud  1 bit.s-1 [amount of information]/[time]  Neper  ratio  Np  log(A/B)  Measure of a ratio A/B. The logarithms are in base 10.  Bel  ratio  B  0.5 Np  Mostly used as decibel (dB): 1 dB = (1/20) Np.  Table V. Accepted non-SI units  Unit of Symbol Equals Note Electronvolt  energy  eV  1.60217733(49).10-19 J Energy to move an electron across a potential difference of 1 V.  Astronomical unit  length  au, AU, ua  1.49597870(30).10+11 m Mean Earth-to-Sun distance. Also denoted as ua.  Atomic mass unit  mass  u  1.6605402(10).10-27 kg 1/12 of the rest mass of an unbound 12C atom in ground state.  Table VI. Units deprecated by  Unit of Symbol Equals Note Nautical mile  length  mile  1852 m  Knot  velocity  knot  1 mile.h-1 A nautical unit.  Are  area  are  100 m2 Hectar  area  ha  100 are  10000 m2  Bar  pressure  bar  100000 Pa  Almost 1 atm = 101325 Pa (an obsolete unit)  Calory  energy  cal  4.1868 J  Note: the conversion factor is fixed by convention.  Ångström  length  Å  10-10 m Used in atomic and molecular physics.  Barn  area  b  10-28 m2 Used in particle physics (collision cross-sections).  Radioactivity and radiation: Curie  Radioactivity  b  3.7*10+10 Bq Note: the conversion factor is fixed by convention.  Röntgen  Radiation dose  R  0.000258 Ci.kg-1 Note: the conversion factor is fixed by convention.  Rad  Radiation dose  rad  0.01 Gy  Rem  Equivalent dose  rem  0.01 Sv