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Copyright: 1996 - 2024 Webmaster:
Kirt
Blattenberger,
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
AirplanesAndRockets.com
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Resistivity (ρ) & Conductivity (σ) of
Metals, Alloys, Rocks, and Soils
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|
 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 cross-sectional area (A) of 0.03309 cm2, 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 Reference Data for Radio
Engineers, 1995, Sams Publishing. Please verify accuracy with a second source. See
rocks and soils table at bottom. Interesting note: The nickel-silver
compound actually contains no silver at all; its name is derived from a silver appearance.
| Alumel |
solid |
33.3 |
0 |
0.0012 |
| Aluminum |
liquid solid |
20.3 2.62 |
670 20 |
.0039 |
| Antimony |
liquid solid |
123 39.2 |
800 20 |
0.0036 |
| Arsenic |
solid |
35 |
0 |
0.0042 |
| Beryllium |
solid |
4.57 |
20 |
|
| Bismuth |
liquid solid |
128.9 115 |
300 20 |
0.004 |
| Boron |
solid |
1.8x1012 |
0 |
|
| Brass (66 Cu, 34 Zn) |
solid |
3.9 |
20 |
0.002 |
| Cadmium |
liquid solid |
34 7.5 |
400 20 |
0.0038 |
| Carbon |
diamond graphite graphene |
5x1020 1400 |
15 20 |
-0.0005 |
| Cerium |
solid |
78 |
20 |
|
| Cesium |
liquid solid |
36.6 20 |
30 20 |
|
| Chromax (15 Cr, 35 Ni, balance Fe) |
solid |
100 |
20 |
0.00031 |
| Chromel |
solid |
70-110 |
0 |
0.00011-0.000054 |
| Chromium |
solid |
2.6 |
0 |
|
| Cobalt |
solid |
9.7 |
20 |
0.0033 |
| Constantan (55 Cu, 45 Ni) |
solid |
44.2 |
20 |
0.0002 |
| Copper (annealed) |
liquid solid |
21.3 1.7241 |
1083 20 |
0.0039 |
| Gallium |
solid liquid |
27 53 |
30 0 |
|
| Gold |
liquid solid |
30.8 2.44 |
1063 20 |
0.0034 |
| Granite |
solid |
1x1013 - 1x1015 |
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|
| Hafnium |
solid |
32.1 |
20 |
|
| Indium |
liquid solid |
29 9 |
157 20 |
0.00498 |
| Iridium |
solid |
5.3 |
20 |
0.0039 |
| Iron |
solid |
9.71 |
20 |
0.0052-0.0062 |
| Kovar A (29, Ni, 17 Co, 0.3 Mn, balance Fe) |
solid |
45-84 |
20 |
|
| Lava flow (basic) Lava, fresh |
liquid |
1x1012 - 1x1013 |
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|
| Lead |
liquid solid |
98 21.9 |
400 20 |
0.004 |
| PbO2 |
solid |
92 |
|
|
| Lithium |
liquid solid |
45 9.3 |
230 20 |
0.003 0.005 |
| Magnesium |
solid |
4.46 |
20 |
0.004 |
| Manganese |
solid |
5 |
20 |
|
| MnO2 |
solid |
6000000 |
20 |
|
| Magnanin (84 Cu, 12 Mn, 4 Ni) |
solid |
44 |
20 |
±0.0002 |
| Mercury |
liquid solid |
95.8 21.3 |
20 -50 |
0.00089 |
| Molybdenum |
solid |
5.17 4.77 |
0 20 |
0.0033 |
| Monel metal (67 Ni, 30 Cu, 1.4 Fe) |
solid |
42 |
20 |
0.002 |
| Neodymium |
solid |
79 |
18 |
|
| Nichrome (65 Ni, 12 Cr, 23 Fe) |
solid |
100 |
20 |
0.00017 |
| Nickel |
solid |
6.9 |
20 |
0.0047 |
| Nickel-Silver (64 Cu, 18 Zn, 18 Ni) |
solid |
28 |
20 |
0.00026 |
| Niobium |
solid |
12.4 |
20 |
|
| Osmium |
solid |
9 |
20 |
0.0042 |
| Palladium |
solid |
10.8 |
20 |
0.0033 |
| Phosphor bronze (4 Sn, 0.5 P, balance Cu) |
solid |
9.4 |
20 |
0.003 |
| Platinum |
solid |
10.5 |
20 |
0.003 |
| Plutonium |
solid |
150 |
20 |
|
| Potassium |
liquid solid |
13 7 |
62 20 |
0.006 |
| Praseodymium |
solid |
68 |
25 |
|
| Rhenium |
solid |
19.8 |
20 |
|
| Rhodium |
solid |
5.1 |
20 |
0.0046 |
| Rubidium |
solid |
12.5 |
20 |
|
| Ruthenium |
solid |
10 |
20 |
|
| Selenium |
solid |
1.2 |
20 |
|
| Silver |
solid |
1.62 |
20 |
0.0038 |
| Sodium |
liquid solid |
9.7 4.6 |
100 20 |
|
| Steel (0.4-0.5 C, balance Fe) |
solid |
13-22 |
20 |
0.003 |
| Steel, manganese (13 Mn, 1 C, 86 Fe) |
solid |
70 |
20 |
0.001 |
| Steel, stainless (0.1 C, 18 Cr, 8 Ni, balance Fe) |
solid |
90 |
20 |
|
| Strontium |
solid |
23 |
20 |
|
| Sulfur |
solid |
2x1023 |
20 |
|
| Tantalum |
solid |
13.1 |
20 |
0.003 |
| Thallium |
solid |
18.1 |
20 |
0.004 |
| Thorium |
solid |
18 |
20 |
0.0021 |
| Tin |
solid |
11.4 |
20 |
0.0042 |
| Titanium |
solid |
47.8 |
25 |
|
| Tophet A (80 Ni, 20 Cr) |
solid |
108 |
20 |
0.00014 |
| Tungsten |
solid |
5.48 |
20 |
0.0045 |
| W2O5 |
solid |
450 |
20 |
|
| WO3 |
solid |
2x1011 |
20 |
|
| Uranium |
solid |
29 |
0 |
0.0021 |
| Zinc |
liquid solid |
35.3 6 |
420 20 |
0.0037 |
| Zirconiumn |
solid |
40 |
20 |
0.0044 |
| Granite |
107 - 109 |
| Lava flow (basic) Lava, fresh |
106 - 107 3x105 - 106 |
| Marble Marble, white Marble, yellow |
4x108 1010 1010 |
| Quartz, vein, massive |
>106 |
| Schist, mica |
107 |
| Shale, bed Shale, nonesuch |
105 104 |
| Limestone Limestone, Cambrian |
104 104 - 105 |
| Sandstone Sandstone, eastern |
105 3x103 - 104 |
| Clay, blue Clay, fire |
2x104 2x105 |
| Clayey earth |
104 - 4x104 |
| Gravel |
105 |
| Sand, dry Sand, moist |
105 - 106 106 - 105 |
Posted July 13, 2018
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