Electromagnetic lagging

Similar to Eq. (II. 1), the energy of two molecules with allowance of electromagnetic lag [44] can be represented in the following form... 

Then, by analogy with Eqs. (II.21) (II.26), we obtain formulas characterizing the molecular interaction of condensed bodies with allowance for electromagnetic lag [44,45] ... 

The calculation of the constant >1 can be performed by a different method. The force of interaction of two plane surfaces with a small gap between the contiguous bodies, i.e., without accounting for electromagnetic lag, can be represented not only by Eq. (11.33), but also in a somewhat different form (the force as calculated for unit contact area) ... 

Determination of Constant of Molecular Interaction with Allowance for Electromagnetic Lag. In this case, we are speaking of the molecular interaction of condensed bodies that are separated by a gap of 100 A or more [44, 45]. 

The values obtained for the constant. 4 loi differ not only quantitatively, but also in the direction of the effect. The calculations without allowance for electromagnetic lag, on the basis of Eq. (11.83), give a negative value for the constant 4iioi, signifying repulsion of the contiguous bodies. In the other cases, the con-... 

These routes that we have considered for calculating the constant Aioi, which characterizes the interaction of two like solids in a liquid medium, are also valid with respect to the constant 102, which in liquid medium determines the adhesion of two unlike solids. The constant. 4102, in contrast to the constant. 4x01, is calculated in accordance with Eq. (11.82), which, the same as (11.83), does not take electromagnetic lag into account. 

Thus, without taking electromagnetic lag into account, calculations of the molecular interaction constant in a liquid medium may give erroneous results. 

Thus, in a liquid medium, electromagnetic lag is not the sole source of molecular interaction (the exponent n is not equal to 3), and this interaction cannot be calculated by the use of Eq. (11.53). At the same time, molecular interaction is not determined by dispersion forces alone since the exponent n is not equal to 2, and Eq. (11.52) cannot be used in calculating the molecular component of adhesive force. 

In a liquid medium, apparently, the molecular forces are governed by the resultant action of the dispersion component and interaction with allowance for electromagnetic lag. In this connection, it is not advisable to separate the constant of molecular interaction into A and B in the case of particle adhesion in a liquid medium. Hence, the molecular interaction of particles with a surface in a liquid medium is characterized by means of a single constant, designated as A. 

The Mackrles [69] considered that molecular forces are the basic source of adhesion, basing their development on Eq. (11.22). Actually, in adhesion in this sort of filtration, there is a gap between the suspension particles and the surface of the filter grains, this gap sometimes being quite considerable. Hence, in determining molecular forces, electromagnetic lag must be taken into account (see Section 6), as was done in [301]. 

Further, a comparison has been made between the molecular and diffu-sional mechanisms of particle precipitation by means of the capture coefficient. The capture coefficient, with and without allowing for electromagnetic lag, is given by... 

Lifshits [55] used quantum electrodynamics to develop a theory for the molecular interaction of condensed macroscopic bodies, allowing for electromagnetic lagging. The value of this theory lies in that the forces of interaction calculated from it agree closely with the earlier-obtained [53, 56] experimental data on the interaction of spherical glass bodies with a plane metallic surface. According to the Lifshits theory, for a small gap between the contiguous surfaces, i.e., in the case H < A, the force of interaction between two similar plane surfaces equals... 

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