The current density \(j_{\mathbf{B}}\) of a species B in a given point of the solution is obtained by multiplying the flux density of that species at the given point by the @F02325@ \(F\) and by the @C00993@ \(z_{\text{B}}\) of the species: \[j_{\mathbf{B}} = z_{\text{B}}\ F\ N_{\mathbf{B}}\] where \(j_{\mathbf{B}}\) is a vector which indicates the direction in which the charges transported by the species B flow and which gives the number of these charges going through a plane oriented perpendicular to the vector, divided by time and by area, and \(N_{\mathbf{B}}\) is the flux density of a minor @C01281@ of the solution with respect to a fixed frame of reference.