# What is flux?

• (noun): (physics) the number of flux changes per unit area.
Synonyms: flux density

## Flux

In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks. A simple and ubiquitous concept throughout physics and applied mathematics is the flow of a physical property in space, frequently also with time variation. It is the basis of the field concept in physics and mathematics, with two principle applications: in transport phenomena and surface integrals. The terms "flux", "current", "flux density", "current density", can sometimes be used interchangeably and ambiguously, though the terms used below match those of the contexts in the literature.

### Some articles on flux:

Convection–diffusion Equation - Derivation
... the control volume where is the total flux and s is a net volumetric source for c ... There are two sources of flux in this situation ... First, diffusive flux arises due to diffusion ...
Spectral Flux Density - Flux Density of The Radiative Field At A Measuring Point - Comparison Between Vector and Scalar Definitions of Flux Density
... In this case, the value of the vector flux density at P1 is the zero vector, while the scalar or hemispheric flux density at P1 in every direction in both ... of the radiation on the detector requires a halving of the energy flux according to Lambert's cosine law the solid angle of a sphere is 4π ... The scalar or hemispheric spectral flux density is convenient for discussions in terms of the two-stream model of the radiative field, which is reasonable ...
Relative Spectral Flux Density
... convenient to display graphical spectra with vertical axes that show the relative spectral flux density ... In this case, the spectral flux density at a given wavelength is expressed as a fraction of some arbitrarily chosen reference value ... Relative spectral flux densities are expressed as pure numbers without any units ...
Secondary Flux
... A secondary flux is a ceramic flux (such as calcium, barium, magnesium or zinc oxide) which does not act as a good flux (i.e ... and by itself has little fluxing effect at pyrometric cone 6 but does act as a flux at cone 8 ... A primary flux is a metal ion such as sodium which acts as a flux at all temperatures ...
Flux As A Surface Integral - Electromagnetism - Poynting Flux
... Using this definition, the flux of the Poynting vector S over a specified surface is the rate at which electromagnetic energy flows through that surface, defined like before The flux of the Poynting ... the Poynting vector is sometimes called the power flux, which is an example of the first usage of flux, above ...

### More definitions of "flux":

• (noun): A flow or discharge.
Synonyms: fluxion
• (noun): Excessive discharge of liquid from a cavity or organ (as in watery diarrhea).
• (verb): Move or progress freely as if in a stream.
Synonyms: flow
• (verb): Become liquid or fluid when heated.
Synonyms: liquefy, liquify
• (noun): In constant change.
Example: "His opinions are in flux"; "the newness and flux of the computer industry"
• (noun): A state of uncertainty about what should be done (usually following some important event) preceding the establishment of a new direction of action.
Example: "The flux following the death of the emperor"
Synonyms: state of flux
• (noun): The rate of flow of energy or particles across a given surface.
• (noun): A substance added to molten metals to bond with impurities that can then be readily removed.

### Famous quotes containing the word flux:

Beauty is our weapon against nature; by it we make objects, giving them limit, symmetry, proportion. Beauty halts and freezes the melting flux of nature.
Camille Paglia (b. 1947)

Sense is a line, the mind is a circle. Sense is like a line which is the flux of a point running out from itself, but intellect like a circle that keeps within itself.
Ralph J. Cudworth (1617–1688)

Death not merely ends life, it also bestows upon it a silent completeness, snatched from the hazardous flux to which all things human are subject.
Hannah Arendt (1906–1975)