Current Density

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Current density

A vector quantity equal in magnitude to the instantaneous rate of flow of electric charge, perpendicular to a chosen surface, per unit area per unit time. If a wire of cross-sectional area A carries a current I, the current density J is I/A. The units of J in the rationalized meter-kilogram-second system are amperes per square meter.

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Current Density


a vector quantity whose magnitude is equal to the electric charge flowing per unit time per unit area, where the area is perpendicular to the direction of motion of the charge. If the charge density (the charge per unit volume) is equal to ρ, then the current density is j = ρv, where v is the average velocity of the ordered flow of the charges. When the distribution of the current density is uniform over the cross section of the conductor, the current I is equal to jS, where S is the cross-sectional area of the conductor.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

current density

[′kər·ənt ‚den·səd·ē]
The current per unit cross-sectional area of a conductor; a specialization of the physics definition. Also known as electric current density.
A vector quantity whose component perpendicular to any surface equals the rate of flow of some conserved, indestructible quantity across that surface per unit area per unit time. Also known as current.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
We could observe also here that at current densities over 0.75 A/[cm.sup.2], the fuel cell polarization curves for flow fields M1 and M3 are close to each other, due to similar ohmic losses.
The results show increase in current densities with increase in BOx loading on the cathode.
The magnitude of fluctuations in current densities (channel noise) depends on the number of ionic channels and, thus, for fixed channel densities ([[rho].sub.Na] = 60 channels/[micro][m.sup.2], [[rho].sub.K] = 18 channels/[micro][m.sup.2]), on the area of the considered membrane patch.
Finally, predicted electric field magnitudes were computed from median current densities observed in the OCC ROI divided by gray matter conductivity found in Table 1.
The effect of pH on electrocoagulation of POME and PW was studied within the pH range of 2-10, at 50[degrees]C and 60[degrees]C for POME and PW, respectively, with varying current densities. Figure 2 shows that the removal efficiency increased significantly when the solution pH was increased to 10, for POME.
A reduction of chloride ions was remarkable at only the lowest current density (i.e., 250 mA/[m.sup.2]), while a slight reduction of chloride ions was observed in the case of higher current densities at identical increment of current density.
The pH 8 needed lower current density, compared with the two other current densities. It was concluded that optimum pH for reaching to microbial standard (MPN 0) was pH 8.
Since observation and source locations are typically well separated, particular singularity treatment is here not necessary, unless the field transformations are combined with additional constraints such as a null-field condition in order to obtain Love equivalent surface current densities [12-15].
For current densities higher than the typical value estimated above, the voltage-dependent sodium channels in the plasma membrane become activated leading to further depolarization of the membrane and initiation of the action potential.
Figure 1 shows the curves of potential as a function of anodizing time in 0.3M [H.sub.3]P[O.sub.4] solution for 15, 45 and 90 minutes with current densities of 10 and 15 mA/[cm.sup.2].