Ohm. Because of that surface resistivity and the surface resistance are often mixed up. In order to differentiate between the two, surface resistiv-ity is often expressed also in Ohm/square (Î©/sq.) which is not a valid unit from the dimensional anal-ysis point of view. 2 Surface resistivity and surface resistance 2.1 Current density and surface cur-
The median age of the world's population was estimated to be 30.1 years in 2016, with the male median age estimated to be 29.4 years and female, 30.9 years.
1 the United States population is equivalent to 4.38% of the total world population. 2  the U.S.A. ranks number 3 in the list of countries by population. 3  The population density in the United States is 35 per Km2 (92 people per mi2).  The median age in the United States is 38.1 years.