Resistivity, electrical, effects

With eveiy change in ion concentration, there is an electrical effect generated by an electrochemical cell. The anion membrane shown in the middle has three cells associated with it, two caused by the concentration differences in the boundaiy layers, and one resulting from the concentration difference across the membrane. In addition, there are ohmic resistances for each step, resulting from the E/I resistance through the solution, boundary layers, and the membrane. In solution, current is carried by ions, and their movement produces a fric tion effect manifested as a resistance. In practical applications, I R losses are more important than the power required to move ions to a compartment wim a higher concentration. 

Without coke backfill, the anode reactions proceed according to Eqs. (7-1) and (7-2) with the subsequent reactions (7-3) and (7-4) exclusively at the cable anode. As a result, the graphite is consumed in the course of time and the cable anode resistance becomes high at these points. The process is dependent on the local current density and therefore on the soil resistivity. The life of the cable anode is determined, not by its mechanical stability, but by its electrical effectiveness. 

In the case of high-sulfur coal, the resistivity of the ash is actually shifted toward higher values closer to the optimum by chemical treatment. In this case the effects of agglomeration of fly ash by the additive cannot be readily distinguished from electrical effects. The unit described in Table IV, burning design coal, was unable to meet particulate emissions compliance levels without additive treatment. 

ELECTRICAL RESISTANCE, HALL EFFECT, DRUDE MODEL, TUNNELING, AND THE LANDAUER FORMULA... 

Figure 6.12 Model electrical equivalent circuit to calculate the leakage current in an electrodialyzer. C cation exchange membrane A anion exchange membrane Re electrical resistance of effective membrane area (cell resistance) Rc electrical resistance of channels between compartment of effective membrane area and internal conduits of concentrated and desalting stream (leakage resistance) Rd electrical resistance of conduits in the inlet and outlet of concentrated and desalting stream in the electrodialyzer (channel resistance).

Electrical effects. Electrical methods are convenient because an electrical signal can be easily processed. Resistance thermometers (including thermistors) and thermocouples are the most widely used. Other electrical methods include noise thermometers using the Johnson noise as a temperature indicator resonant-frequency thermometers, which rely on the temperature dependence of the resonant frequency of a medium, including nuclear quadrupole resonance thermometers, ultrasonic thermometers, and quartz thermometers and semiconductor-diode thermometers, where the relation between temperature and junction voltage at constant current is used. 

The decrease in electrical resistance of selenium during exposure to light was first observed more than hundred years ago. Later a similar behaviour was also found with a number of other materials, but at that time the potential possibilities of the photo-electrical effect were not utilized practically. Today, however, the situation has changed and, for example, energy conversion with photo-voltaic solar cells has become an important technology. 

Electrolytically evolved gas bubbles affect three components of the cell voltage and change the macro- and microscopic current distributions in electrolyzers. Dispersed in the bulk electrolyte, they increase ohmic losses in the cell and, if nonuniformly distributed in the direction parallel to the electrode, they deflect current from regions where they are more concentrated to regions of lower void fraction. Bubbles attached to or located very near the electrodes likewise present ohmic resistance, and also, by making the microscopic current distribution nonuniform, increase the effective current density on the electrode, which adds to the electrode kinetic polarization. Evolution of gas bubbles stirs the electrolyte and thus reduces the supersaturation of product gas at the electrode, thereby lowering the concentration polarization of the electrode. Thus electrolytically evolved gas bubbles affect the electrolyte conductivity, electrode current distribution, and concentration overpotential and the effects depend on the location of the bubbles in the cell. Discussed in this section are the conductivity of bulk dispersions and the electrical effects of bubbles attached to or very near the electrode. Readers interested in the effect of bubbles dispersed in the bulk on the macroscopic current distribution in electrolyzers should see a recent review of Vogt.31... 

Of or relating to the electrical effects of light, including the emission of electrons, the generation of a voltage, or a change in resistance, photosynthesis... 

SME seems to be necessary in order to form a percolation network, but on the other hand too intense mixing resulted in an increase in the electrical resistivity. This effect is particularly pronounced for polyamide 6 composites. 

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