## PHYS345 Electricity and Electronics

**Resistivity**

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

**Resistance of a Cylindrical Conductor**

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 10^{17} ohm-m for an excellent insulator.

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Comments, suggestions, or requests to
ghw@udel.edu.
"http://www.physics.udel.edu/~watson/phys345/class/2-resistivity.html"

Last updated Sept. 2, 1998.

Copyright George Watson, Univ. of Delaware, 1998.