Meter:
The meter is the length of the path
traveled by light in vacuum during a time
interval of 1/299,792,458 second.
Kilogram: The kilogram is the
unit of mass equal to the mass of the
international prototype of kilogram.
Second: The second is the
duration of 9,192,631,770 periods of the
radiation corresponding to the transition between
the two hyperfine levers (F=4, mF=0 to F=3, mF=0)
of the ground state of the cesium 133 atom.
Ampere: The ampere is the
constant current which, if maintained in two
straight parallel conductors of infinite length,
of negligible circular cross-section, and placed
1 meter apart in vacuum, would produce between
these conductors a force equal to 2x10-7 newton
per meter of length.
Named in honour of the 19th-century French
physicist André-Marie Ampére.
Kelvin: The kelvin, unit of
thermodynamic temperature is the fraction
1/273.16 of the thermodynamic temperature of the
triple point of water.
Named in honour of the British physicist William
Thomson, Baron Kelvin.
Mole: The mole is the amount of
substance of a system which contains as many
elementary entities as there are atoms in .012 kg
of carbon 12 (6.0221367x10²³ atoms
"Avogadro's number"). When the mole is
used, the elementary entities must be specified
and may be atoms, molecules, ions, electrons,
other particles, or specified groups of such
particles. In this definition, it is understood
that the carbon 12 atoms are unbound, at rest and
in their ground state.
(A mole also bears the name Avogadro's number, or
Avogadro's constant, in honour of the Italian
physicist Amedeo Avogadro (1776-1856). Avogadro
proposed that equal volumes of gases under the
same conditions contain the same number of
molecules, a hypothesis that proved useful in
determining atomic and molecular weights and
which led to the concept of the mole.)
Candela: The candela is the
luminous intensity, in a given direction, of a
source that emits monochromatic radiation of
frequency 540x1012 Hz and that has a radiant
intensity in that direction of 1/683 watt per
steradian.
|
Examples
of SI Derived Units
| Unit |
Special Name |
Symbol |
Equivalent |
| plane angle |
radian |
rad |
1 |
| solid angle |
steradian |
sr |
1 |
| angular
velocity |
|
|
rad/s |
| angular
acceleration |
|
|
rad/² |
| frequency |
hertz |
Hz |
s-1 |
| speed, velocity |
|
|
m/s |
| acceleration |
|
|
m/s² |
| force |
newton |
N |
kg m/s² |
| pressure,
stress |
pascal |
Pa |
N/m² |
| energy, work,
heat |
joule |
J |
kg m²/s², N m |
| power |
watt |
W |
kg m²/s², J/s |
| power flux
density |
|
|
W/m² |
| linear
momentum, impulse |
|
|
kg m/s, N s |
| angular
momentum |
|
|
kg m²/s, N m s |
| electric charge |
coulomb |
C |
A s |
| electric
potential |
emf volt |
V |
W/A, J/C |
| magnetic flux |
weber |
Wb |
V s |
| resistance |
ohm |
|
V/A |
| conductance |
siemens |
S |
A/V, -1 |
| inductance |
henry |
H |
Wb/A |
| capacitance |
farad |
F |
C/V |
| electric field
strength |
|
|
V/m, N/C |
| electric
displacement |
|
|
C/m² |
| magnetic field
strength |
|
|
A/m |
| magnetic flux
density |
tesla |
T |
Wb/m², N/(A m) |
| Celsius
temperature |
degree Celsius |
C |
K |
| luminous flux |
lumen |
lm |
cd sr |
| illuminance |
lux |
lx |
lm/m² |
| radioactivity |
becquerel |
Bq |
s-1 |
|
