Di-electric constant

The relative di-electric constants of the oil were taken here as 2.65 in the inlet and side zones, and as = 3.00 in the Hertzian zone (pressure effect). As the outlet is mostly filled with air, the di-electric constant here was Ef " ... 

This chapter discusses the electrolytic-solution properties of low-di-electric-constant nematic solvents. Dissolved substances, if electrolytes, can contribute only a fraction of their ions to the conductance because of equilibrium between the free ions and ion pairs. If the solute forms ions through intermediate charge-transfer reactions, additional equilibria must be considered. For nematics, the solvent fluidity is anisotropic, and the conductance depends on the direction of current flow with respect to the orientation of the fluid. The variation of the conductance with temperature is directly related to the variation with temperature of both the ionic equilibrium and the fluidity. 

Table G Definitions of the Electric Field E, the (Di)electric Polarization P, the Electric Displacement D, the Magnetic Field H, the Magnetization M, the Magnetic induction or flux density B, statement of the Maxwell equations, and of the Lorentz Force Equation in Various Systems of Units rat. = rationalized (no 477-), unrat. = the explicit factor 477- is used in the definition of dielectric polarization and magnetization c = speed of light) (using SI values for e, me, h, c) [J.D. Jackson, Classical Electrodynamics, 3rd edition, Wiley, New York, 1999.]. For Hartree atomic u nits of mag netism, two conventions exist (1) the "Gauss" or wave convention, which requires that E and H have the same magnitude for electromagnetic waves in vacuo (2) the Lorentz convention, which derives the magnetic field from the Lorentz force equation the ratio between these two sets of units is the Sommerfeld fine-structure constant a = 1/137.0359895...

The main task of the theory of induction logging is to determine the dependence of the quasistationary electromagnetic field, measured by a probe receiver, on the resistivity of a medium. Our investigations will naturally be based on Maxwell s equations. As was shown in Chapter 1 the problem of field determination can be formulated in the following way. All space can be represented as a sum of areas with constant parameters fii and a, where fii is the magnetic permeability and is the conductivity of area Di. Within every area Di electric and magnetic fields satisfy Helmholtz equations ... 

These interactions (dd, di, ii) are a function of dipole moment and polarizability. It has been shown that the dipole moment cannot be replaced entirely by the use of electrical effect substituent constants as parameters52. This is because the dipole moment has no sign. Either an overall electron donor group or an overall electron acceptor group may have the same value of /x. It has also been shown that the bond moment rather than the molecular dipole moment is the parameter of choice. The dipole moments of MeX and PhX were taken as measures of the bond moments of substituents bonded to sp3- and sp2-hybridized carbon atoms, respectively, of a skeletal group. Application to substituents bonded to sp-hybridized carbon atoms should require a set of dipole moments for substituted ethynes. 

If di-arylethylenes are used as electrochromic substances (in media capable of conducting electric current), applying a 10- to 12-V cyclically changing voltage enhances the optical absorption as described earlier. These changes are readily registered and remain constant for at least 2 years. In order to return to the initial state of the system, it is sufficient to apply a near-UV light impulse for just a few seconds. The record-erase cycles can be repeated more than 1000 times with the same capacity. 

There are two kinds of ionophores charged ones, which are called liquid ion exchangers, and neutral carriers. Because they are mobile in both the free and in the complexed form, mobilities of all species are again part of the selectivity coefficient together with the ion-exchange equilibrium constant. The best-known neutral ionophore is valinomycin (Fig. 6.15a) which shows a 1,000 1 selectivity for K+ in preference to Na+ and no pH dependence. In its uncomplexed form, it is electrically neutral. A better-known representative is di(n-octyl phenyl) phosphonate (Fig. 6.15c), which shows good selectivity for calcium ion and is relatively pH insensitive. 

Dielectric" designates the response of material to an electric field applied across it 0Si or Sia, Greek di or dia means "across"). Recall that a "dielectric constant," e, is a coefficient of proportionality relating a constant electric field E in a material to the electric polarization P of the material in response to that field (note the use of cgs Gaussian units here). 

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