The resistance of a conductor depends on material and geometry. These effects may be separated by considering the resistivity of the material.
Refer to the Play-Doh Experiment
The proportionality constant rho is the resistivity of the conductor, a material property, not a geometrical one. L is the length of the cylinder and A is its cross-sectional area.
There is a wide range of resistivities available, from as low as 10-8 ohm-m for pure metals to as high as 1017 ohm-m for an excellent insulator.
Last updated Sept. 2, 1998.
Copyright George Watson, Univ. of Delaware, 1998.