Resistivity, also referred
to as specific resistance, is dependent on the nature of the material as well as
its volume definition (shape and size). Resistivity is expressed in units that are
the product of resistance and length; e.g., Ω·cm. The symbol most commonly
used for resistivity is rho (ρ).
Conductivity is
the reciprocal of resistivity. Conductivity is expressed in units that are the quotient
of conductance (Siemens) and length; e.g., S/cm. The symbol most commonly used
for resistivity is sigma (σ).
As an example of calculating a volume's resistance, consider the drawing to the
left. Assume 12 AWG copper wire with a resistivity (from the table) of 1.72x10^{6} Ω·cm,
a crosssectional area (A) of 0.03309 cm^{2}, and a length of 1 meter.
Per the given formula, its resistance is:
,
which agrees well with typical specified Ω/km values published by wire manufacturers.
Alpha claims 1.59 Ω/1000' or 5.22 Ω/km.
The table of resistivity values below are pulled from the
Wikipedia website. A wide variation in values can be found in various
sources, so verify the accuracy with a trusted source if critical work is being
done.
Air 
1E9 to 1E15 
1E15 to 1E9 
Aluminum 
2.65E8 
3.77E7 
3.93E3 
Annealed copper 
1.72E8 
5.80E7 
3.93E3 
Arsenic 
3.50E7 
2.86E6 

Bismuth 
129E8 
7.75E5 

Boron 
1.80e10 
5.56E11 

Brass (30% Zn) 
5.99E8 
1.67E7 

Brass (5% Zn) 
3.00E8 
3.34E7 

Calcium 
3.36E8 
2.98E7 
4.10E3 
Carbon (amorphous) 
0.5E3 to 0.8E3 
1.25E3 to 2.00E3 
0.50E3 
Carbon (diamond) 
1E12 
1013 

Carbon (graphite†) 
250E8 to 500E8 
2E5 to 3E5 
Carbon (graphite††) 
3.0E3 
3.3E2 

Carbon steel (1010) 
14.3E8 
6.99E6 

Cobalt 
6.24E8 
1.60E7 
7.00E3 
Constantan 
49.0E8 
2.04E6 
0.008E3 
Copper 
1.68E8 
5.96E7 
4.04E3 
Deionized water 
1.8E5 
4.2E5 

Drinking water 
2E1 to 2E3 
5E4 to 5E2 
Fused quartz 
7.5E17 
1.3E18 

Gallium 
14.0E8 
7.10E6 
4.00E3 
Germanium 
4.6E1 
2.17 
48.0E3 
Glass 
1E11 to 1E15 
1E15 to 1011 
Gold 
2.44E8 
4.11E7 
3.40E3 
Steel (electrical, grainoriented) 
46.0E8 
2.17E6 

Hard rubber 
1E13 
1E14 

Iron 
9.70E8 
1.03E7 
5.00E3 
Lead 
22.0E8 
4.55E6 

Lithium 
9.28E8 
1.08E7 
6.00E3 
Manganese 
144E8 
6.94E5 

Manganin 
48.2E8 
2.07E6 
0.002E3 
Mercury 
98.0E8 
1.02E6 
0.90E3 
Nichrome 
110E8 
6.70E5 
0.40E3 
Nickel 
6.99E8 
1.437 
6.00E3 
Niobium 
14.0E8 
7.006 

PET 
1E21 
1E21 

Phosphor Bronze (0.2% P / 5% Sn) 
11.2E8 
8.94E6 

Platinum 
10.6E8 
9.436 
3.92E3 
Plutonium (0 °C) 
146E8 
6.855 

PTFE (Teflon) 
1E23 to 1E25 
1E25 to 1E23 
Rhodium 
4.33E8 
2.31E7 

Ruthenium 
7.10E8 
1.41E7 

Sea water 
2.1E1 
4.8 

Silicon 
2.30E3 
4.35E4 
75.0E3 
Silver 
1.59E8 
6.30E7 
3.80E3 
Stainless steel 
69.0E8 
1.45E6 
0.94E3 
Sulfur 
1E15 
1016 

Swimming pool water 
3.3E1 to 4.0E1 
0.25 to 0.30 
Tantalum 
1.37E7 
7.63E7 

Tin 
10.9E8 
9.17E6 
4.50E3 
Titanium 
42.0E8 
2.38E6 
3.80E3 
Tungsten 
5.60E8 
1.79E7 
4.50E3 
Ultrapure water 
1.82E09 
5.49E10 

Wood (damp) 
1E3 to 1E4 
1E4 to 1E3 
Wood (oven dry) 
1E14 to 1E16 
1E16 to 1E14 
Zinc 
5.90E8 
1.69E7 
3.70E3 
† parallel to basal plane
†† perpendicular to basal plane
Posted June 7, 2023 (updated)
