The excess conductivity in a surface per unit length and width, symbol κ σ.
Source:
PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 621 (https://doi.org/10.1351/pac197231040577)