Current expression

Current or full-load current expressed as amps (amperes) and drawn by motor at a stated voltage. 

This can be inserted into the current expressions (30) and (32), whose divergences enter into the time development equations for the densities. (Note that the denominator of (76) simplifies greatly in all cases except where the silicon is nearly intrinsic. Here again, if the charge states are equilibrated, n+ and n can be eliminated in favor of n0, via (3), (4), and (75). Whether AH and /or nDH must be retained as distinct variables in the system of differential equations, or whether they, too, can be eliminated in favor of 0, will depend on whether or not they are able to come quickly into local equilibrium with the monatomic species. 

In addition to this, and in contrast with the homogeneous case discussed in Section 5.2.2, the diffusion of P and Q is therefore not perturbed by any homogeneous reaction. If, furthermore, the P/Q electron transfer at the electrode is fast and thus obeys Nernst s law, the diffusive contribution to the current in equations (5.11) and (5.12) is simply equal to the reversible diffusion-controlled Nernstian response, idif, discussed in Section 1.2. The mutual independence of the diffusive and catalytic contributions to the current, expressed as... 

Thus, the ratio between the return (at the time t) and forward (at the time t—t) currents (expressed as the absolute value, since za and zc have, conventionally, opposite signs) is equal to ... 

Electron beam power Product of the acceleration voltage and of the electron beam current, expressed in kW (1 kW =10 mA x 100 kV). 

A summary of limiting current expressions at many hydrodynamic electrodes is given in Table 3. 

Dimensionless current representations also exist. If the electrode is placed at the center of the first volume element in the model, this current will be proportional to the material flux into the first element from the second. For electroactive species A, this flux is given by DMA [fA(2) - fA(l)], where fA(J) is the fractional concentration of A in the Jth element. This fractional flux may be converted to moles of flux through multiplication by C (bulk concentration) and A Ax (volume-element volume, assuming a planar electrode of area A). Appropriate electrochemical conversion and the recognition that this material flux occurs during the interval At yield the current expression... 

Formerly [H20] = 1 was by convention (though pre-1950 Bjernun used the actual [H20]), but the current expression of equilibrium constants in dimensionless form by using ratios of concentrations (activities) to standard states results in the water term being unity since solvent water is, to a very close approximation, in its standard state. 

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 ... 

Closely related to the diffusion layer term is the mass transfer coefficient m,. In a general way, this coefficient is the proportionality constant between the mass transfer flux and the concentration difference between the electrode surface and the bulk of the solution. From the current expression given by Eq. (1.181), one can write... 

Table 3.1 shows the analytical expressions for the roots with physical meaning of the second derivative of the current expression given by Eq. (3.141) with respect to the potential ( ), En, and Em), which correspond to the inflexion points of the current-potential curves shown in Fig. 3.16, given as a function of K. 

Actually, experimental results indicate that the constant in Eq. (3.9) is too small by a factor of V7/3. We now realize that this V7/3 quantity is not empirical but is the appropriate contribution due to the growth of the mercury drop into the solution away from the capillary orifice. Thus, the correct diffusion current expression for a dropping-mercury electrode is... 

If, at places within the oxide layer, the electric field is too large for the exponential expansion utilized above in deriving the linear diffusion equation to be a valid approximation, then the more exact hopping current expression given by eqn. (88) should be utilized instead. Numerical computations are usually easier to carry out in any electric field limit by using the exact microscopic hopping expression (88). 

The different current expressions and reaction orders for each case are summarised in Table 2.2. The relationships between these four cases and sketches of the corresponding concentration profiles are shown in Fig. 2.8. 

Summary of current expressions for each case and the reaction orders with respect to the different reaction variables... 

Case Current expression Reaction order [NADH ] [ site ] L Eqn... 

In the integration for the current expression of Eq. (89) in the complex lower half plane, only the area around the poles where co ek contributes... 

From the current expression in Eq. (109), it is seen that when k is extremely large, the bracketed term on the far right must tend to zero in order that the current remain finite. Thus in these conditions,... 

This current must be equal to the hole current expressed in terms of surface hole densities (Eq. 7.61b). This yields a relation from which the ratio pfp l can be obtained. Substituting it into Eq. (7.61b) leads to... 

Assuming a uniform accessibility of the tip surface, e.g., a uniform concentration of electroactive species, an analytical approximation of the tip feedback current can be derived (see Chapter 5). For convenience, we repeat the main equations here. Such a model represents a thin layer cell (TLC) with a diffusion-limiting current expressed by Eq. (8). The approximate equation for a quasi-reversible steady-state voltammogram is as follows (11) ... 

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