Electric field strength imposed

The tendency for a system at equilibrium to adjust in a manner that minimizes the effect of a change imposed by external factors (such as changes in temperature, pressure or electric field strength). 

Electroosmosis The motion of liquid through a porous medium caused by an imposed electric field. The term replaces the older terms elec-trosmosis and electroendosmosis. The liquid moves with an electroos-motic velocity that depends on the electric surface potential in the stationary solid and on the electric field gradient. The electroosmotic volume flow is the volume flow rate through the porous plug and is usually expressed per unit electric field strength. The electroosmotic pressure is the pressure difference across the porous plug that is required to just stop electroosmotic flow. 

Much more exciting is the possibility of qualitatively new phenomena, which are generically related to flexopolarization. A prominent example is provided by the so-called flexodomains. They appear as the result of an equilibrium transition from the basic planar state if the applied electric field strength exceeds a certain threshold, Er. Flexodomains are stripe patterns parallel to the imposed preferred direction no x, i.e. with a wave vector qc T In contrast to the standard Freedericksz transition, the sign of... 

Measurement by Electromagnetic Effects. The magnetic flow meter is a device that measures the potential developed when an electrically conductive flow moves through an imposed magnetic field. The voltage developed is proportional to the volumetric flow rate of the fluid and the magnetic field strength. The process fluid sees only an empty pipe so that the device has a very low pressure drop. The device is useful for the measurement of slurries and other fluid systems where an accumulation of another phase could interfere with flow measurement by other devices. The meter must be installed in a section of pipe that is much less conductive than the fluid. This limits its appHcabiHty in many industrial situations. 

Limits on Particle Charging. The electrical charge carried by a particle resides on the surface. Thus, a fundamental upper limit for particle electrification may be computed by imposing the constraint that the electric field at the surface can not exceed the dielectric strength of dry air, Eb 30 kV/cm. According to this hypothesis, the upper limit upon surface charge density becomes... 

A number of factors have been investigated as a response to an imposed (dc) electric field. Current strength, specimen shape, time of measurement, applied pressure, and temperature are typical factors which should be considered. 

In practical applications, Joule heating imposes an upper limit on the maximum field strength. The heat W generated per time unit and unit volume V in an electrolyte of a electrical conductivity k is given by ... 

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). 

In the above study, the aim was first to present a soluble model for a confined assembly of independent electrons subjected to a static electric field of arbitrary strength F. These workers achieved the confinement by imposing a harmonic force in addition to the electric field. They aimed, secondly, to relate their results to atomic ions in hot, non-degenerate plasma. 

That index is the mobility, U[, which is the limiting velocity of the ion in an electric field of unit strength. Mobility usually carries dimensions of cm s (i.e., cm/s per V/cm). When a field of strength % is applied to an ion, it will accelerate under the force imposed by the field until the frictional drag exactly counterbalances the electric force. Then, the ion continues its motion at that terminal velocity. This balance is represented in Figure 2.3.4. 

In the study of adsorbates on metals, the most intensively studied systems to date are those involving the chemisorption of CO on various metallic surfaces such as Cu(lOO), Pt(lll), Ni(lOO) and Pd(lOO) [33,34]. At low applied field under UHV, as well as at low applied electrode potential under electrochemical conditions, the VSE of CO is found to be linear as a function of field strength both the carbon/metal vm-c) and the carbon/oxygen (vc o) vibrational frequencies vary linearly with the applied electric field or with the applied electrode potential, respectively [37]. The mere fact that a linear dependence is found in both kinds of experiments (under UHV and in solution) strongly argues in favor of the fact that, in solution, the electrode potential drop at the surface (imposed by the experimentalist) is actually linearly related to the electric field around the chemisorbed molecule. In that sense, one may reasonnably expect an equation of the type ... 

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