First sign of the author's confusion: >a square of copper two millimeters on a side has the same resistance as a square of copper ten millimeters on a side. It

First sign of the author's confusion: >a square of copper two millimeters on a side has the same resistance as a square of copper ten millimeters on a side. It’s counter-intuitive. The phenomenon is perfectly intuitive for anyone who understands DC resistance of metals, and the geometric assumptions of the "sheet resistance" thought experiment. Resistance is proportional to conducter length divided by cross-sectional area. For a sheet conductor, cross-sectional area is thickness times width. A necessary assumption, unstated in the article, is that the hypothetical test circuit somehow makes perfect, uniform electrical contact over the entirety of both of the sheet's chosen "width" edges.