Current, electrical

FIGURE 2.11.1 Sensation of electrical current at different frequencies. The most sensitive region is located at normal power line frequencies. (From Dalziel, C.F., IEEE Spectr., 9, 41, February 1972. With permission.) 

A mule has neither pride of ancestry nor hope of posterity. 

Because there is a tendency for electrical current to flow, like charges away from each other, and unlike charges toward each other, the natural state is electroneutrality, where there are equal numbers of like and unlike charges. Any deviation from electroneutrality is either a transient situation or requires energy to maintain. 

Ohm s law is the equation used to predict the flow of electric current  

If heat and temperature difference are substituted for electric current and voltage difference, then this equation would describe the flow of heat. If mass rate of flow and concentration difference were used instead, the equation would be equivalent to Pick s law for mass movement. Thus, Ohm s law is universal in form, and demonstrates the analogies among effort and flow variables introduced in Section 2.1. 

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Figure 5.52 Passage of electric current through the reservoir...

The pore system is described by the volume fraction of pore space (the fractional porosity) and the shape of the pore space which is represented by m , known as the cementation exponent. The cementation exponent describes the complexity of the pore system i.e. how difficult it is for an electric current to find a path through the reservoir. 

The volume fraction of water (S J and the saturation exponent n can be considered as expressing the increased difficulty experienced by an electrical current passing through a partially oil filled sample. (Note is only a special case of C, when a reservoir... 

The most oommon method for measuring formation resistivity and henoe determining hydrocarbon saturation is by logging with a resistivity tool such as the Laterolog. The tool is designed to force electrical current through the formation adjacent to the borehole... 

A calorimeter is a device used to measure the work that would have to be done under adiabatic conditions to bring about a change from state 1 to state 2 for which we wish to measure AU= U -U This work is generally done by passing a known constant electric current 3 for a known time t through a known resistance R embedded in the calorimeter, and is denoted by where... 

Ionic bonding was proposed by the German physicist Walther Kossel in 1916 in or der to explain the ability of substances such as molten sodium chloride to conduct an electric current He was the son of Albrecht Kossel winner of the 1910 Nobel Prize in physiology or medi cine for early studies in nu cleic acids... 

Electric current ampere A Magnitude of the current that, when flowing through each of two straight parallel conductors of infinite length, of negligible cross-section, separated by 1 meter in a vacuum, results in a force between the two wires of 2 X 10 newton per meter of length. 

The heating of a conductive solution due to the passage of an electric current through the solution. 

The graph of Figure 6.8 illustrates the effect of increasing voltage on the electric current between two electrodes immersed in a gas. The circuit is completed by an external resistance, used to limit the current flow. As shown in Figure 6.8, the discharge can be considered in regions, which are described below. 

Under suitable conditions of pressure and other factors, application of a suitable voltage between electrodes immersed in a gas causes a discharge of electric current through the gas. Different... 

It has been known for many years that strongly heating a metal wire in a vacuum causes emission of electrons from the metal surface. This effect is important for thermionic devices used to control or amplify electrical current, but this aspect of surface emission is not considered here. Rather, the discussion here focuses on the effect of heating a sample substance to a high temperature on a metal wire or ribbon. 

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