The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.
- Stale discussion now. Feedback forwarded to Lydia in this state. Thanks, John F. Lewis (talk) 16:42, 27 April 2014 (UTC)
The Wikidata development team is working on the implementation of the quantity datatype (Bugzilla: 54318). During this office hour (13.Nov.2013) it was announced that:
- Unit conversion will be configurable, but not defined on-wiki. It will draw upon w:GNU Units (see conversion table here) for reference.
- Most probably dimensions (length, speed, etc) will be associated with properties on creation with a configurable default unit (meter, km/h, etc). When setting a value, another unit of the same dimension can be selected.
- On the client wikis, it will (eventually) be possible to specify a unit for display, with the software taking care of the appropriate conversion.
- Feedback is appreciated on which dimensions and units should be implemented first, and also to detect special cases/needs..
Below there are the dimensions mentioned on "Conversion of units". The list of properties with dimension awaiting creation also should be integrated into this list. If you think that we should use or not use any of them, leave a comment.
See talk page
Selection of dimensions for testingEdit
SI PrefixesEdit
Metric prefixes
|
---|
Prefix
|
Symbol
|
1000m |
10n |
Decimal
|
English word[n 1] |
Since[n 2] |
---|
yotta
|
Y
|
10008 |
1024 |
1000000000000000000000000
|
septillion
|
1991
| zetta
|
Z
|
10007 |
1021 |
1000000000000000000000
|
sextillion
|
1991
| exa
|
E
|
10006 |
1018 |
1000000000000000000
|
quintillion
|
1975
| peta
|
P
|
10005 |
1015 |
1000000000000000
|
quadrillion
|
1975
| tera
|
T
|
10004 |
1012 |
1000000000000
|
trillion
|
1960
| giga
|
G
|
10003 |
109 |
1000000000
|
billion
|
1960
| mega
|
M
|
10002 |
106 |
1000000
|
million
|
1960
| kilo
|
k
|
10001 |
103 |
1000
|
thousand
|
1795
| hecto
|
h
|
10002/3 |
102 |
100
|
hundred
|
1795
| deca
|
da
|
10001/3 |
101 |
10
|
ten
|
1795
|
|
10000 |
100 |
1
|
one
|
–
| deci
|
d
|
1000−1/3 |
10−1 |
0.1
|
tenth
|
1795
| centi
|
c
|
1000−2/3
|
10−2 |
0.01
|
hundredth
|
1795
| milli
|
m
|
1000−1 |
10−3 |
0.001
|
thousandth
|
1795
| micro
|
µ
|
1000−2 |
10−6 |
0.000001
|
millionth
|
1960
| nano
|
n
|
1000−3 |
10−9 |
0.000000001
|
billionth
|
1960
| pico
|
p
|
1000−4 |
10−12 |
0.000000000001
|
trillionth
|
1960
| femto
|
f
|
1000−5 |
10−15 |
0.000000000000001
|
quadrillionth
|
1964
| atto
|
a
|
1000−6 |
10−18 |
0.000000000000000001
|
quintillionth
|
1964
| zepto
|
z
|
1000−7 |
10−21 |
0.000000000000000000001
|
sextillionth
|
1991
| yocto
|
y
|
1000−8 |
10−24 |
0.000000000000000000000001
|
septillionth
|
1991
|
- ↑ This table uses the short scale.
- ↑ The metric system was introduced in 1795 with six prefixes. The other dates relate to recognition by a resolution of the General Conference on Weights and Measures.
|
|
Category:Units of length (Q8794341) -- unit of length (Q1978718)
Category:Units of area (Q4393754)
Category:Units of mass (Q7163187)
Dimensions and unitsEdit
Spatial dimensionsEdit
Category:Units of length (Q8794341) -- unit of length (Q1978718)
For all units including historical or marginal use, see: w:Conversion of units#Length
Category:Units of area (Q4393754)
For all units including historical or marginal use, see: w:Conversion of units#Area
Category:Units of volume (Q7163188)
For all units including historical or marginal use, see: w:Conversion of units#Volume
Plane angleEdit
Category:Units of angle (Q9198409)
metric system (Q232405) of angle (Q11352)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
radian (Q33680) (SI unit) |
rad
|
The angle subtended at the center of a circle by an arc whose length is equal to the circle's radius. One full revolution encompasses 2π radians.
|
= 1 rad
|
milliradian |
mrad
|
|
≡ 1×10−3 rad
|
microradian |
μrad
|
|
≡ 1×10−6 rad
|
nanoradian |
nrad
|
|
≡ 1×10−9 rad
|
picoradian |
prad
|
|
≡ 1×10−12 rad
|
angle (Q11352)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
milliradian (Q1065153) (NATO) |
|
≡ 2π/6400 rad
|
≈ 0.981 748×10−3 rad
|
arcminute; minute of arc (Q209426) |
arcmin, amin, am, , MOA, ( m )
|
≡ 1°/60
|
≈ 0.290 888×10−3 rad
|
arcsecond; arcsecond (Q829073) |
arcsec, asec, as, ( s )
|
≡ 1°/3600
|
≈ 4.848 137×10−6 rad
|
milliarcsecond |
mas
|
≡ 1⁄1,000 arcsecond
|
≈ 4.8481368 nrad
|
microarcsecond |
μas
|
≡ 10−6 arcsecond
|
≈ 4.8481368 prad
|
degree (Q28390) |
°
|
≡ 1/360 of a revolution ≡ π/180 rad
|
≈ 17.453 293×10−3 rad
|
gradian (Q208528); gradian; gon |
grad
|
≡ 1/400 of a revolution ≡ 2π/400 rad ≡ 0.9°
|
≈ 15.707 963×10−3 rad
|
hour angle (Q734439) |
( h )
|
≡ 15°
|
≡ π⁄12 rad
|
turn (Q304479) |
rev / rot
|
≡ 1 revolution ≡ 2π rad
|
≡ 2π rad
|
- NOTE: degrees-minutes-seconds and hours-minutes-seconds (astronomy) are sometimes combined to represent a value.
- For all units including historical or marginal use, see: w:Conversion of units#Plane angle
Solid angleEdit
solid angle (Q208476)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
millisteradian |
msr
|
|
= 0.001 sr
|
square degree (Q254532) |
deg²; sq.deg.; (°)²
|
≡ (π/180)² sr
|
≈ 0.30462×10−3 sr
|
steradian (Q177612) (SI unit) |
sr
|
The solid angle subtended at the center of a sphere of radius r by a portion of the surface of the sphere having an area r2. A sphere encompasses 4π sr.[9] |
= 1 sr
|
For all units including historical or marginal use, see: w:Conversion of units#Solid angle
Category:Units of mass (Q7163187)
Other units of mass (Q11423)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
dalton (Q483261) |
u; AMU; Da
|
|
≈ 1.660 538 73×10−27 ± 1.3×10−36 kg
|
atomic unit of mass, electron rest mass |
me |
|
≈ 9.109 382 15×10−31 ± 45×10−39 kg [10] |
carat (Q261247) (metric) |
ct
|
≡ 200 mg
|
= 200 mg
|
Earth mass (Q681996) |
|
|
= 5.97219×1024 kg
|
electronvolt (Q83327) |
eV
|
≡ 1 eV (energy unit) / c2 |
= 1.7826×10−36 kg
|
ounce (Q48013) |
oz av
|
≡ 1/16 lb
|
= 28.349 523 125 g
|
pound (Q100995) |
lb av
|
≡ 0.453 592 37 kg = 7000 grains
|
≡ 0.453 592 37 kg
|
solar mass (Q180892) |
S /
|
|
1.98855 ± 0.00025×1030 kg
|
For all units including historical or marginal use, see: w:Conversion of units#Mass
Category:Units of density (Q7210922)
density (Q29539)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
metric tons per cubic metre
|
t/m3 |
≡ t/m3 |
= 1,000 kg/m3
|
kilogram per cubic metre (SI unit)
|
kg/m3 |
≡ kg/m3 |
= 1 kg/m3 |
gram per cubic metre
|
g/m3 |
≡ t/m3 |
= 0.001 kg/m3
|
kilogram per litre
|
kg/L
|
≡ kg/L
|
=
|
gram per millilitre
|
g/mL
|
≡ g/mL
|
=
|
other units of density (Q29539)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
ounce (avoirdupois) per cubic foot
|
oz/ft3 |
≡ oz/ft3 |
≈ 1.001153961 kg/m3
|
ounce (avoirdupois) per cubic inch
|
oz/in3 |
≡ oz/in3 |
≈ 1.729994044×103 kg/m3
|
ounce (avoirdupois) per gallon (imperial)
|
oz/gal
|
≡ oz/gal
|
≈ 6.236023291 kg/m3
|
pound (avoirdupois) per cubic foot
|
lb/ft3 |
≡ lb/ft3 |
≈ 16.01846337 kg/m3
|
pound (avoirdupois) per cubic inch
|
lb/in3 |
≡ lb/in3 |
≈ 2.767990471×104 kg/m3
|
pound (avoirdupois) per gallon (imperial)
|
lb/gal
|
≡ lb/gal
|
≈ 99.77637266 kg/m3
|
For all units including historical or marginal use, see: w:Conversion of units#Density
Category:Units of time (Q8878351)
Second-derived units of time (Q11471)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
millennium (Q36507) (1000 Julian years) |
|
≡ 1 000 a (see below for definition of year length)
|
= 1000 years
|
century (Q578) (100 Julian years) |
c
|
≡ 100 a (see below for definition of year length)
|
= 100 years
|
decade (Q39911) (10 Julian years) |
dec
|
≡ 10 a (see below for definition of year length)
|
= 10 years
|
Julian year (Q217208) |
a, y, or yr
|
= 365.25 d average, calculated from common years (365 d) plus one leap year (366 d) every four years
|
= 31 557 600 s
|
month (Q5151) (30 SI days) |
mo
|
≡ 30 d[11] |
= 2 592 000 s
|
week (Q23387) (7 SI days) |
wk
|
≡ 7 d
|
= 168 h = 10 080 min = 604 800 s
|
day (Q573) (24 SI-derived hours) |
d
|
= 24 h
|
= 1440 min = 86400 s
|
hour (Q25235) (60 SI-derived minutes) |
h
|
≡ 60 min
|
= 3 600 s
|
minute (Q7727) (60 seconds) |
min
|
≡ 60 s
|
= 60 s
|
other units of time
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
atomic unit of time |
au
|
≡ a0/(α·c)
|
≈ 2.418 884 254×10−17 s
|
Planck time (Q202642) |
|
≡ (G ℏ/c5)½ |
≈ 1.351 211 868×10−43 s
|
svedberg (Q1472674) |
S
|
≡ 10−13 s
|
= 100 fs
|
- NOTE: sometimes year-month-day-hours, etc. are combined into a single representation.
Frequency / angular frequency / rotational speedEdit
frequency (Q11652) (as angular frequency (Q834020))
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
radian per second (Q1063756) |
rad·s−1, rad/s
|
≡ One unit rpm equals one rotation completed around a fixed axis in one minute of time.
|
2π rad/sec = 1 Hz
|
milliradian per second |
mrad·s−1, mrad/s
|
|
|
microradian per second |
μrad·s−1, μrad/s
|
|
|
nanoradian per second |
nrad·s−1, nrad/s
|
|
|
arcsecond per year |
arcsec·y−1 |
|
|
milliarcsecond per year |
mas·y−1 |
|
|
MechanicsEdit
Speed or velocityEdit
Category:Units of velocity (Q7210890)
A velocity consists of a speed combined with a direction; the speed part of the velocity takes units of speed.
AccelerationEdit
Category:Units of acceleration (Q6456385)
momentum (Q41273)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
kilogram - meter per second |
kg m/s
|
|
SI unit ≡ kg m/s ≡ N s
|
Category:Units of force (Q7210873)
See also: Conversion between weight (force) and mass
Pressure or mechanical stressEdit
Category:Units of pressure (Q8890165)
Torque or moment of forceEdit
Category:Units of torque (Q7402026)
Category:Units of energy (Q7163185)
energy (Q11379)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
barrel of oil equivalent |
boe
|
≈ 5.8×106 BTU59 °F |
≈ 6.12×109 J
|
British thermal unit (ISO) |
BTUISO |
≡ 1.0545×103 J
|
= 1.0545×103 J
|
British thermal unit (International Table) |
BTUIT |
|
= 1.055 055 852 62×103 J
|
British thermal unit (mean) |
BTUmean |
|
≈ 1.055 87×103 J
|
British thermal unit (thermochemical) |
BTUth |
|
≈ 1.054 350×103 J
|
British thermal unit (39 °F) |
BTU39 °F |
|
≈ 1.059 67×103 J
|
British thermal unit (59 °F) |
BTU59 °F |
≡ 1.054 804×103 J
|
= 1.054 804×103 J
|
British thermal unit (60 °F) |
BTU60 °F |
|
≈ 1.054 68×103 J
|
British thermal unit (63 °F) |
BTU63 °F |
|
≈ 1.0546×103 J
|
calorie (International Table) |
calIT |
≡ 4.1868 J
|
= 4.1868 J
|
calorie (mean) |
calmean |
1⁄100 of the energy required to warm one gram of air-free water from 0 °C to 100 °C @ 1 atm
|
≈ 4.190 02 J
|
calorie (thermochemical) |
calth |
≡ 4.184 J
|
= 4.184 J
|
Calorie (US; FDA)
|
Cal
|
≡ 1 kcal
|
= 1000 cal = 4184 J
|
calorie (3.98 °C) |
cal3.98 °C |
|
≈ 4.2045 J
|
calorie (15 °C) |
cal15 °C |
≡ 4.1855 J
|
= 4.1855 J
|
calorie (20 °C) |
cal20 °C |
|
≈ 4.1819 J
|
Celsius heat unit (International Table) |
CHUIT |
≡ 1 BTUIT × 1 K/°R
|
= 1.899 100 534 716×103 J
|
cubic centimetre of atmosphere; standard cubic centimetre |
cc atm; scc
|
≡ 1 atm × 1 cm3 |
= 0.101 325 J
|
cubic foot of atmosphere; standard cubic foot |
cu ft atm; scf
|
≡ 1 atm × 1 ft3 |
= 2.869 204 480 9344×103 J
|
cubic foot of natural gas |
|
≡ 1 000 BTUIT |
= 1.055 055 852 62×106 J
|
cubic yard of atmosphere; standard cubic yard |
cu yd atm; scy
|
≡ 1 atm × 1 yd3 |
= 77.468 520 985 2288×103 J
|
electronvolt |
eV
|
≡ e × 1 V
|
≈ 1.602 177 33×10−19 ± 4.9×10−26 J
|
erg (cgs unit) |
erg
|
≡ 1 g·cm2/s2 |
= 10−7 J
|
foot-pound force |
ft lbf
|
≡ g × 1 lb × 1 ft
|
= 1.355 817 948 331 4004 J
|
foot-poundal |
ft pdl
|
≡ 1 lb·ft2/s2 |
= 4.214 011 009 380 48×10−2 J
|
gallon-atmosphere (imperial) |
imp gal atm
|
≡ 1 atm × 1 gal (imp)
|
= 460.632 569 25 J
|
gallon-atmosphere (US) |
US gal atm
|
≡ 1 atm × 1 gal (US)
|
= 383.556 849 0138 J
|
hartree, atomic unit of energy |
Eh |
≡ me·α2·c2 (= 2 Ry)
|
≈ 4.359 744×10−18 J
|
horsepower-hour |
hp·h
|
≡ 1 hp × 1 h
|
= 2.684 519 537 696 172 792×106 J
|
inch-pound force |
in lbf
|
≡ g × 1 lb × 1 in
|
= 0.112 984 829 027 6167 J
|
joule (Q25269) (SI unit) |
J
|
The work done when a force of one newton moves the point of its application a distance of one metre in the direction of the force.[14] |
= 1 J = 1 m·N = 1 kg·m2/s2 = 1 C·V = 1 W·s
|
kilocalorie; large calorie |
kcal; Cal
|
≡ 1 000 calIT |
= 4.1868×103 J
|
kilowatt-hour; Board of Trade Unit |
kW·h; B.O.T.U.
|
≡ 1 kW × 1 h
|
= 3.6×106 J
|
litre-atmosphere |
l atm; sl
|
≡ 1 atm × 1 L
|
= 101.325 J
|
quad |
|
≡ 1015 BTUIT |
= 1.055 055 852 62×1018 J
|
rydberg |
Ry
|
≡ R∞·ℎ·c
|
≈ 2.179 872×10−18 J
|
therm (E.C.) |
|
≡ 100 000 BTUIT |
= 105.505 585 262×106 J
|
therm (US) |
|
≡ 100 000 BTU59 °F |
= 105.4804×106 J
|
thermie |
th
|
≡ 1 McalIT |
= 4.1868×106 J
|
ton of coal equivalent |
TCE
|
≡ 7 Gcalth |
= 29.288×109 J
|
ton of oil equivalent |
TOE
|
≡ 10 Gcalth |
= 41.84×109 J
|
ton of TNT |
tTNT
|
≡ 1 Gcalth |
= 4.184×109 J
|
Power or heat flow rateEdit
power (Q25342) or heat flow rate (Q12160631)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
atmosphere-cubic centimetre per minute |
atm ccm
|
≡ 1 atm × 1 cm3/min
|
= 1.688 75×10−3 W
|
atmosphere-cubic centimetre per second |
atm ccs
|
≡ 1 atm × 1 cm3/s
|
= 0.101 325 W
|
atmosphere-cubic foot per hour |
atm cfh
|
≡ 1 atm × 1 cu ft/h
|
= 0.797 001 244 704 W
|
atmosphere-cubic foot per minute |
atm·cfm
|
≡ 1 atm × 1 cu ft/min
|
= 47.820 074 682 24 W
|
atmosphere-cubic foot per second |
atm cfs
|
≡ 1 atm × 1 cu ft/s
|
= 2.869 204 480 9344×103 W
|
BTU (International Table) per hour |
BTUIT/h
|
≡ 1 BTUIT/h
|
≈ 0.293 071 W
|
BTU (International Table) per minute |
BTUIT/min
|
≡ 1 BTUIT/min
|
≈ 17.584 264 W
|
BTU (International Table) per second |
BTUIT/s
|
≡ 1 BTUIT/s
|
= 1.055 055 852 62×103 W
|
calorie (International Table) per second |
calIT/s
|
≡ 1 calIT/s
|
= 4.1868 W
|
erg per second |
erg/s
|
≡ 1 erg/s
|
= 10−7 W
|
foot-pound-force per hour |
ft lbf/h
|
≡ 1 ft lbf/h
|
≈ 3.766 161×10−4 W
|
foot-pound-force per minute |
ft lbf/min
|
≡ 1 ft lbf/min
|
= 2.259 696 580 552 334×10−2 W
|
foot-pound-force per second |
ft lbf/s
|
≡ 1 ft lbf/s
|
= 1.355 817 948 331 4004 W
|
horsepower (boiler) |
bhp
|
≈ 34.5 lb/h × 970.3 BTUIT/lb
|
≈ 9.810 657×103 W
|
horsepower (European electrical) |
hp
|
≡ 75 kp·m/s
|
= 736 W
|
horsepower (imperial electrical) |
hp
|
≡ 746 W
|
= 746 W
|
metric Horsepower (Q160857) (imperial mechanical) |
hp
|
≡ 550 ft lbf/s
|
= 745.699 871 582 270 22 W
|
metric Horsepower (Q160857) (metric) |
hp
|
≡ 75 m kgf/s
|
= 735.498 75 W
|
litre-atmosphere per minute |
L·atm/min
|
≡ 1 atm × 1 L/min
|
= 1.688 75 W
|
litre-atmosphere per second |
L·atm/s
|
≡ 1 atm × 1 L/s
|
= 101.325 W
|
lusec |
lusec
|
≡ 1 L·µmHg/s [9] |
≈ 1.333×10−4 W
|
poncelet (Q1768929) |
p
|
≡ 100 m kgf/s
|
= 980.665 W
|
square foot equivalent direct radiation |
sq ft EDR
|
≡ 240 BTUIT/h
|
≈ 70.337 057 W
|
ton of air conditioning |
|
≡ 2000 lbs of ice melted / 24 h
|
≈ 3 504 W
|
ton of refrigeration (imperial) |
|
≡ 2240 lb × iceIT / 24 h: iceIT = 144°F × 2326 J/kg.°F
|
≈ 3.938 875×103 W
|
ton of refrigeration (IT) |
|
≡ 200 lbs × iceIT / 24 h: iceIT = 144° × 2326 J/kg.°F
|
≈ 3.516 853×103 W
|
watt (Q25236) (SI unit) |
W
|
The power which in one second of time gives rise to one joule of energy.[14] |
= 1 W = 1 J/s = 1 N·m/s = 1 kg·m2/s3 |
Flow (volume)Edit
Flow
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
cubic foot per minute
|
CFM[citation needed] |
≡ 1 ft3/min
|
= 4.719474432×10−4 m3/s
|
cubic foot per second
|
ft3/s
|
≡ 1 ft3/s
|
= 0.028316846592 m3/s
|
cubic inch per minute
|
in3/min
|
≡ 1 in3/min
|
= 2.7311773×10−7 m3/s
|
cubic inch per second
|
in3/s
|
≡ 1 in3/s
|
= 1.6387064×10−5 m3/s
|
cubic metre per second (SI unit)
|
m3/s
|
≡ 1 m3/s
|
= 1 m3/s
|
gallon (US fluid) per day
|
GPD[citation needed] |
≡ 1 gal/d
|
= 4.381263638×10−8 m3/s
|
gallon (US fluid) per hour
|
GPH[citation needed] |
≡ 1 gal/h
|
= 1.051503273×10−6 m3/s
|
gallon (US fluid) per minute
|
GPM[citation needed] |
≡ 1 gal/min
|
= 6.30901964×10−5 m3/s
|
litre per minute
|
LPM[citation needed] |
≡ 1 L/min
|
= 1.6×10−5 m3/s
|
ViscosityEdit
Dynamic viscosityEdit
Kinematic viscosityEdit
ElectromagnetismEdit
Electric currentEdit
Electric chargeEdit
Electric dipoleEdit
Electric dipole
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
atomic unit of electric dipole moment |
ea0
|
|
≈ 8.478 352 81×10−30 C·m[18] |
coulomb meter |
C·m
|
|
= 1 C · 1 m
|
debye |
D
|
= 10−10 esu·Å
|
= 3.33564095×10−30 C·m [19] |
Electromotive force, electric potential differenceEdit
Voltage, electromotive force
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
abvolt (cgs unit) |
abV
|
≡ 1×10−8 V
|
= 1×10−8 V
|
statvolt (cgs unit) |
statV
|
≡ c· (1 μJ/A·m)
|
= 299.792 458 V
|
volt (SI unit) |
V
|
The difference in electric potential across two points along a conducting wire carrying one ampere of constant current when the power dissipated between the points equals one watt.[14] |
= 1 V = 1 W/A = 1 kg·m2/(A·s3)
|
Electrical resistanceEdit
Electrical resistance
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
ohm (Q47083) (SI unit) |
Ω
|
The resistance between two points in a conductor when one volt of electric potential difference, applied to these points, produces one ampere of current in the conductor.[14] |
= 1 Ω = 1 V/A = 1 kg·m2/(A2·s3)
|
CapacitanceEdit
capacitance (Q164399) - ability to store electric charge
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
farad (Q131255) (SI unit)
|
F
|
The capacitance between two parallel plates that results in one volt of potential difference when charged by one coulomb of electricity.[14] |
= 1 F = 1 C/V = 1 A2·s4/(kg·m2)
|
InductanceEdit
inductance (Q177897)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
henry (Q163354) (SI unit) |
H
|
The inductance of a closed circuit that produces one volt of electromotive force when the current in the circuit varies at a uniform rate of one ampere per second.[14] |
= 1 H = 1 Wb/A = 1 kg·m2/(A·s)2
|
Magnetic fluxEdit
Category:Units of magnetic flux (Q7722730)
magnetic flux (Q177831)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
maxwell (Q608697) (CGS unit)
|
Mx
|
≡ 10−8 Wb[20] |
= 1×10−8 Wb
|
weber (Q170804) (SI unit)
|
Wb
|
Magnetic flux which, linking a circuit of one turn, would produce in it an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second.[14] |
= 1 Wb = 1 V·s = 1 kg·m2/(A·s2)
|
Magnetic flux densityEdit
Category:Units of magnetic field (Q7722737)
What physicists call en:Magnetic field is called Magnetic flux density by electrical engineers and magnetic flux density (Q30204) by applied mathematicians and electrical engineers.
TemperatureEdit
Category:Units of temperature (Q7210885)
en:Conversion of units of temperature
Information entropyEdit
information entropy (Q204570)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
Relation to bits
|
---|
SI unit |
J/K
|
≡ J/K
|
= 1 J/K
|
|
nat; nip; nepit |
nat
|
≡ kB
|
= 1.380 650 5(23)×10−23 J/K
|
|
bit (Q8805) ; shannon |
bit; b; Sh
|
≡ ln(2) × kB
|
= 9.569 940 (16)×10−24 J/K
|
= 1 bit
|
ban; hartley |
ban; Hart
|
≡ ln(10) × kB
|
= 3.179 065 3(53)×10−23 J/K
|
|
nibble |
|
≡ 4 bits
|
= 3.827 976 0(64)×10−23 J/K
|
= 22 bit
|
byte (Q8799) |
B
|
≡ 8 bits
|
= 7.655 952 (13)×10−23 J/K
|
= 23 bit
|
kilobyte (Q79726) (decimal) |
kB
|
≡ 1 000 B
|
= 7.655 952 (13)×10−20 J/K
|
= 8×103 bit = 8000 bit
|
kilobyte (kibibyte) |
KB; KiB
|
≡ 1 024 B
|
= 7.839 695 (13)×10−20 J/K
|
= 213 bit = 8192 bit
|
Often, information entropy is measured in shannons, whereas the (discrete) storage space of digital devices is measured in bits. Thus, uncompressed redundant data occupy more than one bit of storage per shannon of information entropy. The multiples of a bit listed above are usually used with this meaning. Other times the bit is used as a measure of information entropy and is thus a synonym of shannon.
Luminous intensityEdit
The candela is the preferred nomenclature for the SI unit.
luminous intensity (Q104831)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
candela (Q83216) (SI base unit); candle
|
cd
|
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 watt per steradian.[1] |
= 1 cd
|
candlepower (new)
|
cp
|
≡ cd The use of candlepower as a unit is discouraged due to its ambiguity.
|
= 1 cd
|
candlepower (old, pre-1948)
|
cp
|
Varies and is poorly reproducible.[22] Approximately 0.981 cd.[9] |
≈ 0.981 cd
|
LuminanceEdit
Category:Units of luminance (Q7722791)
Luminous fluxEdit
Category:Units of luminous flux (Q7722767)
IlluminanceEdit
Category:Units of illuminance (Q7722749)
illuminance (Q194411)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
footcandle; lumen per square foot
|
fc
|
≡ lm/ft2 |
= 10.763910417 lx
|
lumen per square inch
|
lm/in2 |
≡ lm/in2 |
≈ 1,550.0031 lx
|
lux (Q179836) (SI unit)
|
lx
|
≡ lm/m2 |
= 1 lx = 1 lm/m2 |
phot (Q901492) (CGS unit)
|
ph
|
≡ lm/cm2 |
= 1×104 lx
|
RadiationEdit
Radiation - source activityEdit
Category:Units of radioactivity (Q7722761)
Please note that although becquerel (Bq) and hertz (Hz) both ultimately refer to the same SI base unit (s−1), Hz is used only for periodic phenomena, and Bq is only used for stochastic processes associated with radioactivity.[24]
Radiation - exposureEdit
Category:Units of radiation dose (Q7163135)
exposure (Q336938) (Radiation - exposure)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
coulomb per kilogram (SI unit) |
C/kg
|
|
= 1C / 1kg
|
roentgen (Q321017) (cgs unit) |
R
|
1 R ≡ 2.58×10−4 C/kg[20] |
= 2.58×10−4 C/kg
|
The roentgen is not an SI unit and the NIST strongly discourages its continued use.[25]
Radiation - absorbed doseEdit
Category:Units of radiation dose (Q7163135)
Radiation - equivalent doseEdit
Although the definitions for sievert (Sv) and gray (Gy) would seem to indicate that they measure the same quantities, this is not the case. The effect of receiving a certain dose of radiation (given as Gy) is variable and depends on many factors, thus a new unit was needed to denote the biological effectiveness of that dose on the body; this is known as the equivalent dose and is shown in Sv. The general relationship between absorbed dose and equivalent dose can be represented as
- H = Q · D
where H is the equivalent dose, D is the absorbed dose, and Q is a dimensionless quality factor. Thus, for any quantity of D measured in Gy, the numerical value for H measured in Sv may be different.[27]
Concentration and chemical compositionEdit
Category:Units of chemical measurement (Q8919525)
- Instead of ppm (and similar ppb, ppt) use the correct dimensions (µg/g, ng/g, µl/l) or for numbers without dimensions 10^-6 (or 10^-4 %). Billion and Trillion are not used the same everywhere and the notation is ambiguous because nobody can readily tell what the basis of the ratio (volume, mass, molar) is. --Tobias1984 (talk) 11:48, 14 November 2013 (UTC)
Thermodynamic unitsEdit
Category:Units of chemical measurement (Q8919525)
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
Specific enthalpy (Q161064) (SI-standard) |
kJ/mol, kJ/kg
|
energy per (mass or molar unit)
|
|
Specific entropy (Q5380792)
|
kJ/mol K, kJ/kg K
|
energy per (mass or molar unit) per kelvin
|
|
Specific heat capacity (Q179388)
|
kJ/mol K, kJ/kg K
|
energy per (mass or molar unit) per kelvin
|
|
Loudness
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
sone (Q676380) |
N |
|
|
Loudness level
Name of unit
|
Symbol
|
Definition
|
Relation to SI units
|
---|
phon (Q781545) |
L_N |
|
|
Dimensionless unitsEdit
PercentageEdit
- Unit = currency symbol. With the qualifiers "point in time".--Micru (talk) 11:28, 22 November 2013 (UTC)
Category:Currency (Q6959409)
Notes and referencesEdit
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 The International System of Units, Section 2.1 (8 ed.), Bureau International des Poids et Mesures, 2006, retrieved August 26, 2009
- ↑ author=jobs url title=The astronomical unit gets fixed : Nature News & Comment doi=10.1038/nature.2012.11416 publisher=Nature.com |date=2012-09-14 |accessdate=2013-08-31
- ↑ "NIST Reference on Constants, Units, and Uncertainty."(2006). National Institute of Standards and Technology. Retrieved February 22, 2008.
- ↑ The International Astronomical Union and Astronomical Units
- ↑ International System of Units, 8th ed. (2006), Bureau International des Poids et Mesures, Section 4.1 Table 8.
- ↑ P. Kenneth Seidelmann, Ed. (1992). Explanatory Supplement to the Astronomical Almanac. Sausalito, CA: University Science Books. p. 716 and s.v. parsec in Glossary.
- ↑ Cite error: Invalid
<ref>
tag; no text was provided for refs named nbs
- ↑ Barry N. Taylor, Ed.,NIST Special Publication 330: The International System of Units (SI) (2001 Edition), Washington: US Government Printing Office, 43,"The 12th Conference Generale des Poids et Mesures (CGPM)…declares that the word “litre” may be employed as a special name for the cubic decimetre".
- ↑ 9.0 9.1 9.2 9.3 Cite error: Invalid
<ref>
tag; no text was provided for refs named howmany
- ↑ CODATA Value: atomic unit of mass. (2006). National Institute of Standards and Technology. Retrieved 16 September 2008.
- ↑ Pedersen O. (1983). "Glossary" in Coyne, G., Hoskin, M., and Pedersen, O. Gregorian Reform of the Calendar: Proceedings of the Vatican Conference to Commemorate its 400th Anniversary. Vatican Observatory. Available from Astrophysics Data System.
- ↑ Tom Benson. (2010.) "Mach Number" in Beginner's Guide to Aeronautics. NASA.
- ↑ CODATA Value: atomic unit of force. (2006). National Institute of Standards and Technology. Retrieved September 14, 2008.
- ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 Comité International des Poids et Mesures, Resolution 2, 1946, retrieved August 26, 2009
- ↑ 15.00 15.01 15.02 15.03 15.04 15.05 15.06 15.07 15.08 15.09 15.10 15.11 15.12 15.13 15.14 15.15 Barry N. Taylor, (April 1 995), Guide for the Use of the International System of Units (SI) (NIST Special Publication 811), Washington, DC: US Government Printing Office, pp. 57–68.
- ↑ Barry N. Taylor, (April 1995), Guide for the Use of the International System of Units (SI) (NIST Special Publication 811), Washington, DC: US Government Printing Office, p. 5.
- ↑ International System of Units, 8th ed. (2006), Bureau International des Poids et Mesures, Section 4.1 Table 7.
- ↑ The NIST Reference on Constants, Units, and Uncertainty, 2006, retrieved August 26, 2009
- ↑ Robert G. Mortimer Physical chemistry,Academic Press, 2000 ISBN 0-12-508345-9, page 677
- ↑ 20.0 20.1 20.2 NIST Guide to SI Units, Appendix B.9, retrieved August 27, 2009
- ↑ Standard for the Use of the International System of Units (SI): The Modern Metric System IEEE/ASTM SI 10-1997. (1997). New York and West Conshohocken, PA: Institute of Electrical and Electronics Engineers and American Society for Testing and Materials. Tables A.1 through A.5.
- ↑ The NIST Reference on Constants, Units, and Uncertainty, retrieved August 28, 2009
- ↑ Ambler Thompson & Barry N. Taylor. (2008). Guide for the Use of the International System of Units (SI). Special Publication 811. Gaithersburg, MD: National Institute of Standards and Technology. p. 10.
- ↑ 24.0 24.1 The International System of Units, Section 2.2.2., Table 3 (8 ed.), Bureau International des Poids et Mesures, 2006, retrieved August 27, 2009
- ↑ The NIST Guide to the SI (Special Publication 811), section 5.2, 2008, retrieved August 27, 2009
- ↑ Ambler Thompson & Barry N. Taylor. (2008). Guide for the Use of the International System of Units (SI). Special Publication 811. Gaithersburg, MD: National Institute of Standards and Technology. p. 5.
- ↑ Comité international des poids et mesures, 2002, Recommendation 2, retrieved August 27, 2009
- Notes
The above discussion is preserved as an archive. Please do not modify it. Subsequent comments should be made in a new section.