Electrical Conductivity - Elements and other Materials (original) (raw)

Conductors are materials with loosely attached valence electrons - electrons can drift freely between the atoms
Insulators have structures where the electrons are bound to the atoms by ionic or covalent bonds - almost no current can flow
Semiconductors are insulating materials where the bonds can be broken with applied voltage - electrons can be released and moved from one vacated valence site to another.

Electrical Conductivity

Electrical conductivity or specific conductivity is the measure of a material's ability to conduct electric current. Conductivity is the reciprocal (inverse) of electrical resistivity.

Electrical conductivity is defined as the ratio of the current density to the electric field strength and can be expressed as

σ = J / E (1)

where

σ = electrical conductivity (1/ohms m, 1/Ω m, siemens/m, S/m, mho/m)

J = current density (amps/m2)

E = electric field strength (volts/m)

One siemens - S - is equal to the reciprocal of one ohm and is also referred to as one mho.

Electrical Conductivity of some Common Materials

Electrical Conductivity - Elements and other Materials

Product	Electrical Conductivity - σ - (1/Ω m, S/m, mho/m)
Aluminum	37.7×106
Beryllium	31.3×106
Cadmium	13.8×106
Calcium	29.8×106
Chromium	7.74×106
Cobalt	17.2×106
Copper	59.6×106
Copper - annealed	58.0×106
Gallium	6.78×106
Gold	45.2×106
Iridium	19.7×106
Iron	9.93×106
Indium	11.6×106
Lithium	10.8×106
Magnesium	22.6×106
Molybdenum	18.7×106
Nickel	14.3×106
Niobium	6.93×106
Osmium	10.9×106
Palladium	9.5×106
Platinum	9.66×106
Potassium	13.9×106
Rhenium	5.42×106
Rhodium	21.1×106
Rubidium	7.79×106
Ruthenium	13.7×106
Silver	63×106
Sodium	21×106
Strontium	7.62×106
Tantalum	7.61×106
Technetium	6.7×106
Thallium	6.17×106
Thorium	6.53×106
Tin	9.17×106
Tungsten	18.9×106
Zinc	16.6×106
Seawater	4.5 - 5.5
Water - Drinking	0.0005 - 0.05
Water - Deionized	5.5×10-6

1 S/m = 104 μS/cm = mho/m
1 S/cm = 10-2 S/m
1 1/Ω m = S/m = 3.28 1/Ω ft = 3.28 S/ft

Electrical Conductivity of Elements relative to Silver

Electrical Conductivity of Elements relative to Silver

Element	Electrical Conductivity relative to Silver(%)
Silver	100.0
Copper	94.6
Gold	71.7
Aluminum	59.8
Beryllium	49.7
Calcium	47.3
Magnesium	35.9
Rhodium	33.5
Sodium	33.0
Barium	30.6
Tungsten	30.0
Molybdenum	29.7
Cobalt	27.3
Zinc	26.3
Nickel	22.6
Cadmium	21.9
Ruthenium	21.7
Cesium	20.0
Indium	18.4
Osmium	17.3
Lithium	17.1
Uranium	16.5
Manganese	15.8
Iron	15.8
Platinum	15.3
Palladium	15.1
Tin	14.6
Titanium	13.7
Iridium	13.5
Rubidium	12.4
Chromium	12.3
Tantalum	12.1
Steel	12.0
Thallium	9.8
Lead	8.4
Columbium	5.1
Vanadium	5.0
Arsenic	4.9
Antimony	3.6
Mercury	1.8
Bismuth	1.4
Tellurium	0.0

Electrical Conductivity of Highly Purified Water

Electrical conductivity of highly purified water

Electrical Resistivity

Conductivity is the reciprocal (inverse) of electrical resistivity. Electrical resistivity can be expressed as

ρ = 1 / σ (2)

where

ρ = electrical resistivity (ohm m2/m, ohm m)

Resistance of a Conductor

The resistance for a conductor can be expressed as

R = ρ l / A (3)

where

R = resistance (ohms, Ω)

l = length of conductor (m)

A = cross sectional area of conductor (m2)

Example - Resistance of a Wire

The resistance of 1000 m copper wire gauge #10 with cross sectional area 5.26 mm2 can be calculated as

R = (1.724×10-8 ohm m2/m) (1000 m) / ((5.26 mm2) (10-6 m2/mm2))

= 3.2 ohm

Resistivity and Conductivity Conversion

Resistivity and Conductivity Conversion

Grains/gal as CaCO3	ppm as CaCO3	ppm NaCl	Conductivity μmho/cm	Resistivity MΩ/cm
99.3	1700	2000	3860	0.00026
74.5	1275	1500	2930	0.00034
49.6	850	1000	1990	0.00050
24.8	425	500	1020	0.00099
9.93	170	200	415	0.0024
7.45	127	150	315	0.0032
4.96	85.0	100	210	0.0048
2.48	42.5	50	105	0.0095
0.992	17.0	20	42.7	0.023
0.742	12.7	15	32.1	0.031
0.496	8.50	10	21.4	0.047
0.248	4.25	5.0	10.8	0.093
0.099	1.70	2.0	4.35	0.23
0.074	1.27	1.5	3.28	0.30
0.048	0.85	1.00	2.21	0.45
0.025	0.42	0.50	1.13	0.88
0.0099	0.17	0.20	0.49	2.05
0.0076	0.13	0.15	0.38	2.65
0.0050	0.085	0.10	0.27	3.70
0.0025	0.042	0.05	0.16	6.15
0.00099	0.017	0.02	0.098	10.2
0.00070	0.012	0.015	0.087	11.5
0.00047	0.008	0.010	0.076	13.1
0.00023	0.004	0.005	0.066	15.2
0.00012	0.002	0.002	0.059	16.9