##
Resistance of a Cylinder

In this formula, length and area are geometric properties of the cylinder;
the ratio L/A has dimensions of reciprocal length.
The Greek symbol "rho" above stands for resistivity, a property of the material
making up the cylinder,
usually reported in ohm-cm.
The separation of the dependence of a physical quantity
into geometric and material parts is typical.

Note that the resistivity determined for Play-Doh ranged from 10 to 20 ohm-cm,
depending on the color. Compare this with a good conductor: copper has a
resistivity of 0.000002 ohm-cm.
Thus 10 cm of Play-Doh has the same resistance as one million meters of copper
wire of the same diameter!

"http://www.physics.udel.edu/~watson/scen103/cylinder.html"

Last updated March 11, 1999.

Copyright George Watson, Univ. of Delaware, 1996.