- This article is about the concept of flux in science and mathematics. For other uses of the word, see flux (disambiguation).
In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.
First, in the field of heat transport and mass transport (fluid dynamics, hydrogeology, aron flux chemical engineering), flux is defined as the amount of a given quantity that flows through a unit area per unit time (Bird, Stewart, and aeon flux movie Lightfoot, Transport Phenomenon, 1960). Flux in this definition is a vector.
Second, in the field of electromagnetism, the magnetic flux or electric flux is the integral of the magnetic or electric vector field over a finite surface. The result of this integration is a scalar quantity (Lorrain and Corson, Electromagnetic Fields and Waves, 1962).
One could argue, based on the work of James Clerk Maxwell (1892 Treatise on Electricity and Magnetism) that the transport definition precedes the more recent way the term is used in electromagnetism. The specific quote from Maxwell is "In the case of fluxes, magnetic flux we have to take the integral, over a surface, of the flux through every element of the surface. The result of this operation is called the surface integral of the flux. It represents aeon flux the movie the quantity where can i purchase a flux capacitor which passes through the surface."
In addition to these common mathematically defined definitions, there are many more loose usages found in fields such as biology.
Transport phenomenon
Flux definition and theorems
There are many fluxes used in the study of transport phenomena. Each type of flux has its own distinct unit of measurement along with distinct physical constants. Five of the most common forms of flux from the transport literature are stainless ep flux steel flux defined as:
- Momentum flux, the rate of momentum moving across a unit area (N/m2). (Newtonian fluid, viscous flow)
- Heat flux, the rate of heat flow across a unit area (J/(m2 s)). (Fourier's Law)
- Chemical flux, the rate of movement of moles across a unit area (moles/(m2 s). (Fick's first law)
- Mass flux, the rate of mass flow across a unit area (kg/(m2 s). (An alternate form of Fick's law that includes the grams per mole term to convert moles to mass)
- Volumetric flux, the rate of volume flow across a unit area (m3/(m2 s). (Darcy's law)
These fluxes are vectors at each salt flux point in space, and have a definite magnitide and direction. Also, one can take the divergence aeon flux cartoons of any of these fluxes to determine the accumulation rate of the flux capacitor quantity in a control volume around a given point in space. magnetic flux lines For incompressible flow, the divergence of the volume flux is zero.
The fundamental laws that govern this process include:
- Newton's law of viscosity
- Fourier's law of convection
- Fick's law of diffusion.
- Darcy's law of groundwater flow
Thermal systems
In thermal systems, the flux is the rate of heat flow per area per time (J/(m2 s)) aeon flux dvd (Carslaw and Jaeger, Conduction of Heat in Solids, degassing flux flux density Second Edition, 1959). This definition of heat flux fits the original definition of Maxwell (1892).
Chemical diffusion
Flux, or diffusion, flux capacitor prop for gaseous molecules magnetic flux density can be related to the function:
where N is the total number of gaseous particles, k is Boltzmann's constant, T is the relative temperature in kelvins, and σab is the mean free path between the molecules a and b.
Chemical flux is also defined in Ficks's first law as:
J = -D grad(C) where D is the molecular diffuision coefficient (m2/s) and C is the concentration weld aeon flux cartoon pictures tutorial flux core ( moles/m3) (Bird, Stewart, and Lightfoot, Transport Phenomenon, 1960). This flux has units of moles/(m2 s) and fits the original definition of flux (Maxwell, 1892).
Electro-magnetism
Flux definition and theorems
An example of the second definition of flux is the magnitude of a river's current, that is, the amount of water that flows through a cross-section of the river each second. The amount of sunlight that lands on a patch turner flux of ground each second is also a kind of flux. To better understand the concept of flux in Electromagnetism, imagine a butterfly net. The amount eon flux of air moving through the net at any lead solder flux given instant in time is the flux. If the wind speed is high, then the flux through the net is large. If the net is made bigger, then the flux would be larger even though the wind speed is the same. For the most air to move through the net, the opening of the net must be facing solar flux the direction the wind is blowing. If the net opening is parallel to the wind, then no wind will be moving through the net. (These examples are not very good because they rely on a transport process and as stated in the introduction, aeon flux episode where can i buy a flux capacitor replica reviews axial flux motor transport flux is defined differently than E+M flux.)
As a mathematical concept, flux is represented by the surface integral of a vector field,
where F is a vector field, dA is the area element of the surface S, directed as the surface normal, and Φf is the resulting flux.
The surface has to be orientable, i.e. two sides can be distinguished: the surface does not fold back aeon flux trailer onto itself. Also, the surface has to be actually oriented, aeon flux gallery i.e. we use a convention as to flowing which way is counted positive; flowing backward is then counted negative.
The surface normal is directed accordingly, usually by the magnetic flux meter right-hand rule.
Conversely, back to the future flux capacitor one can consider the flux the more fundamental quantity, and call the vector field the flux flux cored density.
Often solder flux a vector field is drawn by curves (field lines) aeon flux videos following the "flow"; the magnitude magnetic lines of flux of the vector field is then the aeon flux line density, and the flux through a surface is the number of lines. Lines aeon flux trailer download originate adipic acid + flux from areas of positive divergence (sources) and end at areas of negative divergence (sinks).
See also the image at right: the number of red arrows passing through a unit area is the flux density, the curve encircling the red arrows denotes the boundary of the surface, and the orientation of the arrows with respect to the surface denotes the sign of the inner product of the vector field with the surface normals.
If the surface encloses a 3D region, usually the surface is oriented such that the outflux is counted positive; the opposite is the influx.
The divergence theorem states that the net outflux through a closed surface, in other words the net outflux from a 3D region, is found by adding the local net outflow from each point in the region (which is expressed by the divergence).
If the surface is aeon flux pics radiative transfer definition flux radiance not closed, it has an oriented curve as boundary. Stokes theorem states that the flux of the curl of a vector field is the path integral of the vector field over this axial flux permanent magnet generator boundary. This path integral is also called circulation, especially in fluid dynamics. Thus the curl is the circulation density.
We can apply the flux and these flux capacitor kit theorems to many disciplines in which we see currents, forces, etc., applied through areas.
Maxwell's equations
The flux of electric and magnetic field aeon flux movie trailer lines is frequently discussed in electrostatics. This is because in Maxwell's equations in integral form involve integrals like above for electric and magnetic fields.
For instance, Gauss's law states flux capacitor images that the flux of the electric field out of a closed surface is proportional to the electric charge enclosed in the surface flux (regardless of how that charge is distributed). The constant of proportionality is the reciprocal of the permittivity of free space.
Its integral form is:
where is the electric field, is the area of a differential square on the surface A with an outward facing surface normal defining its direction, is the charge enclosed by the surface, is the permittivity of free space flux of pink indians and is the integral over the surface A.
Either or is called the electric flux.
Faraday's law of induction in integral form aeon flux downloadable is:
The flux bindings magnetic field density, also called magnetic flux density, is denoted by . Its flux is called the magnetic flux. The time-rate of change of the magnetic flux through a loop of wire is minus the electromotive force created in that wire. The direction is such that if current is allowed to pass through the wire, the electromotive force will cause a current which "opposes" the change in magnetic field by itself producing a magnetic field opposite to the change. This is the basis for inductors and many electric generators.
Electromagnetic radiation
For electromagnetic radiation, the flux of the Poynting vector through a surface is the power, or energy per unit time, passing through that surface.
Flux in biology
General biology usage
In general, 'flux' in biology relates to movement of a substance between compartments. There are several cases where the concept of 'flux' is important.
- The movement of molecules across a membrane: in this case, flux is defined by the rate of diffusion or transport of a substance across a permeable membrane. Except in the case of active transport, net flux is directly proportional to the concentration difference across the membrane, the surface area of the membrane, and the membrane permeability constant.
- In ecology, flux is often considered at the ecosystem level - for instance, accurate determination of carbon fluxes (at a regional and global level) is essential for modeling the causes and consequences of global warming.
- Metabolic flux refers to the rate of flow of metabolites along a metabolic pathway, or even through a single enzyme. A calculation may also be made of carbon (or other elements, e.g. nitrogen) flux. It is dependent on a number of factors, including: enzyme concentration; the concentration of precursor, product, and intermediate metabolites; post-translational modification of enzymes; and the presence of metabolic activators or repressors. Metabolic control analysis provides a framework for understanding metabolic fluxes and their constraints.
An archaic use in biology
Flux is also an archaic aluminum flux term for dysentery, but also seems to cover any extensive flow of fluid from the body, so there's bloody flux core welding flux, etc.
See also
- Carbon flux
- Electron flux
- Energy flux
- Explosively pumped flux compression generator
- Fast Flux Test Facility
- Fluid dynamics
- Flux quantization
- Flux pinning
- Gauss's law
- Heat flux
- Latent heat flux
- Luminous flux
- Magnetic flux
- Magnetic flux quantum
- Neutron flux
- Poynting flux
- Poynting theorem
- Proton flux
- Rapid single flux quantum
- Sound energy flux
- Flux capacitor
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Electronics Topics
The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.
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