Total current, expression

Current Efficiency the ratio of the rate of a specified electrochemical reaction expressed as a current or current density (anodic or cathodic) to the total current or current density (anodic or cathodic) flowing. It is usually expressed as a percentage. 

The enhancement in luminous efficiency achieved by inserting an ultrathin interlayer between the ITO and NPB is mainly due to the reduction of hole injection from ITO to NPB in OLEDs. For a simple approximation, luminous efficiency (rj) can be related directly to a ratio of the recombination current (/r) to the total current density of OLEDs (/tot). If one denotes the current contributions from holes and electrons in OLEDs as. /h and /e, respectively, then the sum of hole and electron currents, /tot. /h + /e, and tj can be expressed as... 

The membrane and diffusion-media modeling equations apply to the same variables in the same phase in the catalyst layer. The rate of evaporation or condensation, eq 39, relates the water concentration in the gas and liquid phases. For the water content and chemical potential in the membrane, various approaches can be used, as discussed in section 4.2. If liquid water exists, a supersaturated isotherm can be used, or the liquid pressure can be assumed to be either continuous or related through a mass-transfer coefficient. If there is only water vapor, an isotherm is used. To relate the reactant and product concentrations, potentials, and currents in the phases within the catalyst layer, kinetic expressions (eqs 12 and 13) are used along with zero values for the divergence of the total current (eq 27). 

Figure 10. Resistor-network representation of porous-electrode theory. The total current density, i, flows through the electrolyte phase (2) and the solid phase (1) at each respective end. Between, the current is apportioned on the basis of the resistances in each phase and the charge-transfer resistances. The charge-transfer resistances can be nonlinear because they are based on kinetic expressions.

The total current is obtained by integrating this expression over the entire distance range, i.e. from xc to °°,... 

The current in the resistor, iR, is in phase with the applied voltage while the current in the capacitor leads the applied voltage by 90° as illustrated in Figure 8.9b. To obtain an expression for the total current i, we must find the vector sum of ic and iR as follows ... 

As the diamagnetic term is set to zero, the procedure is named CTOCD-DZ. Total current becomes completely paramagnetic in form, and contains two terms that are expressed within the original coordinates system as a function of r, L e. 

One method by which transformers may be rated for suitability to handle harmonic loads is by k factor ratings. The k factor is equal to the sum of the square of the harmonic frequency currents (expressed as a ratio of the total RMS current) multiplied by the square of the harmonic frequency numbers ... 

The expression of the total current is the sum of the partial currents corresponding to the different steps is ... 

As in the case of an EE process, the total current for a molecule capable of producing k electron transfers (reaction scheme (3.V)) can be expressed as a product of two functions which depend on the potential and on time and electrode geometry, respectively ... 

The total current efficiency (Q) can be expressed as the product of two efficiencies ... 

To calculate the total current we should substitute the expressions for the wave functions (37)-(39), and summarize all contributions [291]. As a result the Landauer formula is obtained. We present the calculation for the transmission function. First, after substitution of the wave functions we have for the partial current going through the system... 

Mathematical expressions of concentrations, cAs and cBs at the surface of cathode, can be obtained.18 The total current density in the electrolyte is described as... 

Equations (3) or (4), with refinements as necessary for "local field" effects, are an appropriate and useful basis for discussion of various models of non-conducting solutions of biological species considered in I. In many cases, however, solutions of interest have appreciable ionic concentrations in the natural solvent medium and the polymer or other solute species may also have net charges. Under these conditions, the electrical response is better considered in terms of the total current density Jfc(t) defined and expressed by linear response theory as... 

The details of the calculation of the voltammetric profiles can be consulted in the specialized literature8. Here we give the expression for a reversible reaction in which only the adsorbed species O and R contribute to the total current. The reason for this is to enable a comparison between the expressions for this situation and for thin-layer... 

In their work, Andrieux and Saveant analyse the behaviour in terms of the characteristic current densities for each process. This has the advantage that, in general, the expressions for these characteristic current densities are fairly straightforward and obvious and, therefore, easily derived. In the case where the different processes involved are strictly first-order, the reciprocal of total current density can be obtained by combining the reciprocals of the current densities for the individual steps. For example, the limiting current density, //., for a reaction at the surface of a rotating disc coated by a permeable membrane is given by... 

Instantaneous nucleation — This is the case when all nuclei of the new phase are formed within a short time period after supersaturating the parent phase. Then the nuclei only grow, which means that what we call instantaneous nucleation is the process of growth of a constant number N() of supercritical clusters. In this case the theoretical expression for the total current density j o (t) reads... 

At steady state, Equations 6.48 and 6.49 are equal to zero, and the total current of methanol oxidation is expressed as... 

Equation (6.171) shows the direct relation between the electrical conductance of the solution and the phenomenological coefficient. Similar relations are obtained by measuring the fraction of the total current that is carried by each ion, also under the conditions V/li, = 0. This fraction is called the Hittorf transference number (t,) and is expressed by... 

Equation (3.24) also expresses the total current as a sum of contributions from each of the electrode areas. They can be related to the potential loss... 

In order to obtain the impedance response for this reaction, an expression for the total current density is needed in terms of the Feiradaic and charging current density, i.e.,... 

Equation (42) expresses the total current from both the electrodes regardless of the limiting one. The user can follow any of the two definitions for the capacity of the battery (Eqs 38 or 42) however, Eq. (38) gives a closer value to the real capacity of the battery than Eq. (42). Equation (38) is commonly used when building and testing batteries. 

Current density refers to the total current flow in kiloamperes divided by the anode electrode area in square meters, expressed as kA/m. High-current densities are desirable, particularly for electrochemical j rocesses, which yield unstable products. With current densities of 2-3 kA/m", electrolytic products of the diaphragm cell are rapidly moved from the sites of formation, which decreases side reactions and maximizes current efficiencies [14]. High-current densities, however, increase heat generation, anode wear, and the operating voltage so that lower current densities (and more cells) are better if the cells can be made cheaply. 

For reactions controlled by both activation and mass transfer, the total current density is expressed as follows and known as Koutecky-Levich plots ... 

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