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Power is a scalar quantity. Specifying power in particular systems may require attention to other quantities; for example, the power involved in moving a ground vehicle is the product of the aerodynamic drag plus traction force on the wheels, and the velocity of the vehicle.
A root-power quantity is a quantity such as voltage, current, sound pressure, electric field strength, speed, or charge density, the square of which, in linear systems, is proportional to power. [3] The term root-power quantity refers to the square root that relates these quantities to power. The term was introduced in ISO 80000-1 § Annex C ...
The quantity proportional to the number of particles in a sample, with the Avogadro constant as the proportionality constant: mole (mol) N: extensive, scalar Luminous intensity: I v: Wavelength-weighted power of emitted light per unit solid angle: candela (cd) J: scalar
In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit).
The neper is the change in the level of a root-power quantity when the root-power quantity changes by a factor of e, that is 1 Np = ln(e) = 1, thereby relating all of the units as nondimensional natural log of root-power-quantity ratios, 1 dB = 0.115 13... Np = 0.115 13.... Finally, the level of a quantity is the logarithm of the ratio of the ...
Electric power is the rate of transfer of electrical energy within a circuit.Its SI unit is the watt, the general unit of power, defined as one joule per second.Standard prefixes apply to watts as with other SI units: thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively.
If the power quantity P is proportional to F 2, and if the reference value of the power quantity, P 0, is in the same proportion to F 0 2, the levels L F and L P are equal. The neper, bel, and decibel (one tenth of a bel) are units of level that are often applied to such quantities as power, intensity, or gain. [6] The neper, bel, and decibel ...
In physics and many other areas of science and engineering the intensity or flux of radiant energy is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy. [a] In the SI system, it has units watts per square metre (W/m 2), or kg⋅s −3 in base units.