Induced electric field induction

In a d.c. system the current distribution through the cross-section of a current-canying conductor is uniform as it consists of only the resistance. In an a.c. system the inductive effect caused by the induced-electric field causes skin and proximity effects. These effects play a complex role in determining the current distribution through the cross-section of a conductor. In an a.c. system, the inductance of a conductor varies with the depth of the conductor due to the skin effect. This inductance is further affected by the presence of another current-carrying conductor in the vicinity (the proximity effect). Thus, the impedance and the current distribution (density) through the cross-section of the conductor vaiy. Both these factors on an a.c. system tend to increase the effective... 

Faraday s law of induction, E = where E is the induced electric field, V the velocity of motion, and B the intensity of magnetic induction, is the basis for at least two types of electromagnetic flowmeters. In such flowmeters, a uniform magnetic induction is established transverse to the flow in a pipe and the flow of the metered fluid generates a potential difference at suitable detecting electrodes. 

Consider the interaction of a neutral, dipolar molecule A with a neutral, S-state atom B. There are no electrostatic interactions because all the miiltipole moments of the atom are zero. However, the electric field of A distorts the charge distribution of B and induces miiltipole moments in B. The leading induction tenn is the interaction between the pennanent dipole moment of A and the dipole moment induced in B. The latter can be expressed in tenns of the polarizability of B, see equation (Al.S.g). and the dipole-mduced-dipole interaction is given by... 

The inductively coupled plasma [19] is excited by an electric field which is generated by an RF current in an inductor. The changing magnetic field of this inductor induces an electric field in which tire plasma electrons are accelerated. The helicon discharge [20] is a special type of inductively coupled RF discharge. 

A cLirrent-earrying conducior produces an electric field around it which induces a back e.m.f. and causes an inductive effect. This e.m.f. is produced in the conductor hy its own electric field cutting the conductor. It is more dense at the centre and becomes less at the surface. The conducior thus has a higher inductance al the centre than at the surface, and causes an uneven distribution of current... 

The discussion above has been more or less empirical and descriptive. However, considerable effort has been made to interpret 3-SCS on a more physical basis. Electric-field effects (71-75) were invoked to explain signal shifts of 3-carbon atoms induced by protonation of amines (157,158) (cf. Section II-B-3). This approach was later extended to other functionalities by Schneider and coworkers, who assumed that the SEF component (E2) rather than inductive properties of the substituents should be responsible for 3-SCS (113). They found fairly linear correlations of 3-SCS(X ) and 3-SCS(X ) in cyclohexyl derivatives (76) and attributed the difference between these for a given X to a widening of the C -Cp-Cv bond angle by 2.2° in the axial conformer (114,159). The decrease of 3-SCS in the order primary Cp —> secondary Cp — tertiary Cp — quaternary Cp was explained by electron-charge polarization in the Cp-C" bond(s) induced by the LEF component of the C -X dipole, which is already of significance at this distance, though ( 2) still dominates (160). Such an electron flow toward the 3 carbon is expected to be much more pronounced in C-C than in C-H bonds because of the polarizability difference (aCH = 0.79 acc = 1.12) (150,151,160). 

Elastic deformation of the director, induced by a magnetic induction or electric field, in a uniformly aligned, thin sample of a nematic confined between two surfaces. 

An important induced dipole component of pairs involving molecules is multipolar induction. Specifically, the lowest-order multipole consistent with the symmetry of H2 is the electric quadrupole. Each H2 molecule may be thought of as being surrounded by an electric field of quadrupolar symmetry that rotates with the molecule.-In that field, a collisional partner X is polarized, thus giving rise to an induced dipole moment which in turn is capable of emitting and absorbing light. For like pairs, molecule 1 will induce a dipole in molecule 2 and 2 will induce one in 1. In... 

A rotation of the H2 molecule through 180° creates an identical electric field. In other words, for every full rotation of a H2 molecule, the dipole induced in the collisional partner X oscillates twice through the full cycle. Quadrupole induced lines occur, therefore, at twice the (classical) rotation frequencies, or with selection rules J — J + 2, like rotational Raman lines of linear molecules. Orientational transitions (J — J AM 0) occur at zero frequency and make up the translational line. Besides multipole induction of the lowest-order multipole moments consistent with... 

If at least one of the interacting particles is a molecule, further induction mechanisms arise. Molecules are surrounded by an electric field which may be viewed as a superposition of multipole fields. A collisional partner will be polarized in the multipole field and thus give rise to induced dipole components. In the case of symmetric diatoms like H2 or N2, the lowest-order multipole is a quadrupole and asymptotically, for R - 00, the quadrupole-induced dipole may be written as [288, 289]... 

Separation of Electronic and Nuclear Motions. The polarizabilities of the ground state and the excited state can follow an electronic transition, and the same is true of the induced dipole moments in the solvent since these involve the motions of electrons only. However, the solvent dipoles cannot reorganize during such a transition and the electric field which acts on the solute remains unchanged. It is therefore necessary to separate the solvent polarity functions into an orientation polarization and an induction polarization. The total polarization depends on the static dielectric constant Z), the induction polarization depends on the square of the refractive index n2, and the orientation polarization depends on the difference between the relevant functions of D and of n2 this separation between electronic and nuclear motions will appear in the equations of solvation energies and solvatochromic shifts. 

Objects having a dipole can be set into rotational motion by applying a torque by means of an electric field [95], Electrorotation is the rotation of particles as a consequence of the induction of dipole moments and torque exertion by a rotating electric field. Coupled electrorotation (CER) uses static external fields which are spatially fixed to induce dipoles in two or more adjacent particles. This creates oscillating components of the electric field, finally resulting in a rotating electric field (for more details, refer to the original literature [95]). 

When a polar molecule and a non-polar molecule approach each other, the electric field of the polar molecule distorts the electron charge distribution of the non-polar molecule and produces an induced dipole moment within it. The interaction of the permanent and induced dipoles then results in an attractive force. This induction contribution to the electrostatic energy is always present when two polar molecules interact with each other. 

Induction of New Phenomena by Imposed Gradients. Studies on the effects of imposed electric fields on chemical waves (see below on signal propagation) show that phenomena can be induced in the system by the imposed gradient that do not exist in the field free medium. For example, it was found (l l) that for a system wherein only one type of wave existed in the field free case, two stable types of waves exist in the system subject to the field. This "induction of multiplicity" implies that beyond a critical value of the applied field strength new phenomena may set in that are not simple distortions of field free patterns. Another strictly imposed field effect is found in the case of a new two dimensional crescent shaped wave that occurs when a circular wave is subjected to a supracritical field (15). 

For multi-molecular assemblies one has to consider whether the total interaction energy can be written as the sum of pairwise interactions. The first-order electrostatic interaction is exactly pairwise additive, the dispersion only up to second order (in third order a generally small three-body Axilrod-Teller term appears [73]) while the induction is not at all pairwise it is non-linearly additive due to the interference of electric fields from different sources. Moreover, for polar systems the inducing fields are strong enough to change the molecular wave functions significantly. 

Induction forces brought about by the operation of a surface electric field on induced or permanent dipoles of resident molecules... 

For n > 0, it is only the induction part of v l that contributes due to the density dependence in the induced dipoles via the electric fields. 

Numerous studies have been performed on the dynamic generation from DCLs of either molecular receptors for substrates or substrates for receptors [35-39, 46]. Work in our group has been directed in particular towards the influence of physical and chemical stimuli on the behavior of DCLs, as for instance in the case of the constitutional dynamic reorganization exerted by temperature and protonation on imine libraries [45], the induction of liquid crystal properties by an electric field acting on a dynamic library [47], or component selection induced by cation binding in a folded dynamer chain [48] (see also below). 

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