Conductance (other)
Conductance may refer to: * Conductance (graph), a measure in graph theory * Electrical conductance, the ability for electric charge to flow in a certain path * Fluid conductance, the ability for fluid to transmit through materials See also * Conductivity (other) * Thermal conductance (other) For Thermal conductance see: * Thermal contact conductance * Thermal conduction Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as it ...

Conductance (graph)
In graph theory the conductance of a graph measures how "well-knit" the graph is: it controls how fast a random walk on converges to its stationary distribution. The conductance of a graph is often called the Cheeger constant of a graph as the analog of its counterpart in spectral geometry. Since electrical networks are intimately related to random walks with a long history in the usage of the term "conductance", this alternative name helps avoid possible confusion. The conductance of a cut (S, \bar S) in a graph is defined as: :\varphi(S) = \frac where the are the entries of the adjacency matrix for , so that :a(S) = \sum_ \sum_ a_ is the total number (or weight) of the edges incident with . is also called a volume of the set S \subseteq V. The conductance of the whole graph is the minimum conductance over all the possible cuts: : \phi(G) = \min_\varphi(S). Equivalently, conductance of a graph is defined as follows: : \phi(G) := \min_\frac.\, For a -regular graph ...
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Electrical Conductance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with mechanical friction. The SI unit of electrical resistance is the ohm (), while electrical conductance is measured in siemens (S) (formerly called the 'mho' and then represented by ). The resistance of an object depends in large part on the material it is made of. Objects made of electrical insulators like rubber tend to have very high resistance and low conductance, while objects made of electrical conductors like metals tend to have very low resistance and high conductance. This relationship is quantified by resistivity or conductivity. The nature of a material is not the only factor in resistance and conductance, however; it also depends on the size and shape of an object because these properties are extensive rather than i ...
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Fluid Conductance
Fluid conductance is a measure of how effectively fluids are transported through a medium or a region. The concept is particularly useful in cases in which the amount of fluid transported is linearly related to whatever is driving the transport. For example, the concept is useful in the flow of liquids through permeable media, especially in hydrology in relation to river and lake bottoms. In this case, it is an application of intrinsic permeability to a unit of material with a defined area and thickness, and the magnitude of conductance affects the rate of groundwater recharge or interaction with groundwater. This parameter is often used in such computer modelling codes as MODFLOW. Conductance is also a useful concept in the design and study of vacuum systems. Such systems consist of vacuum chambers and the various flow passages and pumps that connect and maintain them. These systems are common in physical science laboratories and many laboratory apparatus as well, such as mass s ...
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Conductivity (other)
Conductivity may refer to: *Electrical conductivity, a measure of a material's ability to conduct an electric current **Conductivity (electrolytic), the electrical conductivity of an electrolyte in solution ** Ionic conductivity (solid state), electrical conductivity due to ions moving position in a crystal lattice *Hydraulic conductivity, a property of a porous material's ability to transmit water *Thermal conductivity, an intensive property of a material that indicates its ability to conduct heat See also * Conductance (other) *Superconductivity Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic flux fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike ...