|
Definiciones de las unidades de SI
Untitled Page
- ampere (A)
-
The ampere is that constant current that, 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
2.10−7 newton per meter of length.
- candela (cd)
-
The candela is the luminous intensity, in a given direction, of a source that emits
monochromatic radiation of frequency 540 X 1012 hertz and that has a radiant intensity
in that direction of 1/683 watt per steradian.
- coulomb (C)
-
The coulomb is the quantity of electricity transported in 1 second by a current
of 1 ampere.
- farad (F)
-
The farad is the capacitance of a capacitor between the plates of which there appears
a difference of potential of 1 volt when it is charged by a quantity of electricity
equal to 1 coulomb.
- henry (H)
-
The henry is the inductance of a closed circuit in which an electromotive force
of 1 volt is produced when the electric current in the circuit varies uniformly
at a rate of 1 ampere per second.
- kelvin (K)
-
The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic
temperature of the triple point of water
- kilogram (kg)
-
The kilogram is the unit of mass; it is equal to the mass of the international prototype
of the kilogram. (The international prototype of the kilogram is a particular cylinder
of platinum-iridium alloy that is preserved in a vault at Sévres, France,
by the International Bureau of Weights and Measures.)
- lumen (lm)
-
The lumen is the luminous flux emitted in a solid angle of 1 steradian by a uniform
point source having an intensity of 1 candela.
- meter (m)
-
The meter is the length equal to the distance traveled by light, in vacuum, in a
time of 1/299,792,458 second.
- mole (mol)
-
The mole is the amount of substance of a system that contains as many elementary
entities as there are carbon atoms in 0.012 kg of carbon 12. The elementary entities
must be specified and may be atoms, molecules, ions, electrons, other particles,
or specified groups of such particles.
- newton (N)
-
The newton is that force that gives to a mass of 1 kilogram an acceleration of 1
meter per second per second.
- ohm (Ω)
-
The ohm is the electric resistance between two points of a conductor when a constant
difference of potential of 1 volt, applied between these two points, produces in
this conductor a current of 1 ampere, this conductor not being the source of any
electromotive force.
- radian (rad)
-
The radian is the plane angle between two radii of a circle that cut off on the
circumference an arc equal in length to the radius.
- steradian (sr)
-
The steradian is the solid angle that, having its vertex in the center of a sphere,
cuts off an area of the surface of the sphere equal to that of a square with sides
of length equal to the radius of the sphere.
- second (s)
-
The second is the duration of 9,192,631,770 periods of the radiation corresponding
to the transition between the two hyperfine levels of the ground state of the cesium-133
atom.
- volt (V)
-
The volt is the difference of electric potential between two points of a conducting
wire carrying a constant current of 1 ampere, when the power dissipated between
these points is equal to 1 watt.
- watt (W)
-
The watt is the power that gives rise to the production of energy at the rate of
1 joule per second.
- weber (Wb)
-
The weher is the magnetic flux that, linking a circuit of one turn, produces in
it an electromotive force of 1 volt as it is reduced to zero at a uniform rate in
1 second.
|
|
| 2010 Novasyon 
RSS
Twitter
Facebook
Digg
YouTube
Delicious
