Abstract
A finite‐element method is applied to the problem of potential distribution around a Luggin‐Haber capillary placed perpendicularly to the planar working electrode for the cases when overpotential is absent and when there is overpotential which is linear to current density. Approximate equations are presented for the IR‐potential drop between the working electrode and the Luggin‐Haber capillary as functions of the outer and inner radii of the capillary tip, the distance from the capillary tip to the working electrode, conductivity of the solution, and average current density. Approximate equations which relate the measured overpotential to the true overpotential, the IR‐potential drop, and the relevant parameters are also presented. In the presence of overpotential or polarization, it has been shown that the measured potential can be regarded as a sum of the true overpotential and the IR‐potential drop, provided that the tip of the Luggin‐Haber capillary is placed no closer from the electrode surface than a distance equal to the outer diameter of the capillary tip.