Energy flux is the rate of transfer of
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of hea ...
through a surface. The quantity is defined in two different ways, depending on the context:
# Total rate of energy transfer (not per unit area);
SI units: W = J⋅s
−1.
#
Specific
Specific may refer to:
* Specificity (disambiguation)
* Specific, a cure or therapy for a specific illness
Law
* Specific deterrence, focussed on an individual
* Specific finding, intermediate verdict used by a jury in determining the fina ...
rate of energy transfer (total normalized per unit
area
Area is the quantity that expresses the extent of a region on the plane or on a curved surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an ope ...
);
SI unit
The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. ...
s: W⋅m
−2 = J⋅m
−2⋅s
−1:
#* This is a vector quantity, its components being determined in terms of the normal (perpendicular) direction to the surface of measurement.
#* This is sometimes called ''energy
flux density'', to distinguish it from the first definition.
#*
Radiative flux,
heat flux, and
sound energy flux
Sound power or acoustic power is the rate at which sound energy is emitted, reflected, transmitted or received, per unit time. It is defined as "through a surface, the product of the sound pressure, and the component of the particle velocity, at ...
are specific cases of this meaning.
See also
*
Energy flow (ecology)
Energy flow is the flow of energy through living things within an ecosystem. All living organisms can be organized into producers and consumers, and those producers and consumers can further be organized into a food chain. Each of the levels wi ...
*
Flux
*
Irradiance
*
Poynting vector
*
Stress–energy tensor
*
Energy current
References
{{reflist
Physical quantities
Vector calculus