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  2. Per-unit system - Wikipedia

    en.wikipedia.org/wiki/Per-unit_system

    Conversion of per-unit quantities to volts, ohms, or amperes requires a knowledge of the base that the per-unit quantities were referenced to. The per-unit system is used in power flow, short circuit evaluation, motor starting studies etc. The main idea of a per unit system is to absorb large differences in absolute values into base relationships.

  3. Power (physics) - Wikipedia

    en.wikipedia.org/wiki/Power_(physics)

    In the International System of Units, the unit of power is the watt, equal to one joule per second. 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 ...

  4. Intensity (physics) - Wikipedia

    en.wikipedia.org/wiki/Intensity_(physics)

    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.

  5. Poynting vector - Wikipedia

    en.wikipedia.org/wiki/Poynting_vector

    In physics, the Poynting vector (or Umov–Poynting vector) represents the directional energy flux (the energy transfer per unit area, per unit time) or power flow of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m 2 ); kg/s 3 in base SI units.

  6. Radiant intensity - Wikipedia

    en.wikipedia.org/wiki/Radiant_intensity

    Radiant intensity is used to characterize the emission of radiation by an antenna: [2], = (), where E e is the irradiance of the antenna;; r is the distance from the antenna.; Unlike power density, radiant intensity does not depend on distance: because radiant intensity is defined as the power through a solid angle, the decreasing power density over distance due to the inverse-square law is ...

  7. Surface power density - Wikipedia

    en.wikipedia.org/wiki/Surface_power_density

    Pd = the power density, E = the RMS electric field strength in volts per meter, H = the RMS magnetic field strength in amperes per meter. [6] The above equation yields units of W/m 2. In the USA the units of mW/cm 2, are more often used when making surveys. One mW/cm 2 is the same power density as 10 W/m 2.

  8. Stream power - Wikipedia

    en.wikipedia.org/wiki/Stream_power

    Critical unit stream power is the amount of stream power needed to displace a grain of a specific size, it is given by the equation: ω 0 = τ 0 ν 0 {\displaystyle \omega _{0}=\tau _{0}\nu _{0}} where τ 0 is the critical shear stress of the grain size that will be moved which can be found in the literature or experimentally determined while v ...

  9. Power density - Wikipedia

    en.wikipedia.org/wiki/Power_density

    Power density, defined as the amount of power (the time rate of energy transfer) per unit volume, is a critical parameter used across a spectrum of scientific and engineering disciplines. This metric, typically denoted in watts per cubic meter (W/m 3 ), serves as a fundamental measure for evaluating the efficacy and capability of various ...