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Resistivity, Conductivity and Temperature Coefficients for some Common Materials

Resistivity, conductivity and temperature coefficients for some common materials as silver, gold, platinum, iron and more - Including a tutorial explanation of resistivity and conductivity

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The factor in the resistance which takes into account the nature of the material is the resistivity.

Material Resistivity Coefficient 2)
- ρ -
(ohm m)		 Temperature
Coefficient 2)
per degree C		 Conductivity
- σ -
(1 /Ωm)
Aluminum 2.65 x 10-8 3.8 x 10-3 3.77 x 107
Antimony 41.8 x 10-8    
Beryllium 4.0 x 10-8    
Bismuth 115 x 10-8    
Cadmium 7.4 x 10-8    
Carbon (graphite)1) 3 - 60 x 10-5 -4.8 x 10-3
Chromel (alloy of chromium and aluminum) 0.58 x 10-3
Chromium 13 x 10-8    
Cobalt 9 x 10-8    
Constantan 49 x 10-8 0 0.20 x 107
Copper 1.724 x 10-8 4.29 x 10-3 5.95 x 107
Eureka   0.1 x 10-3  
Iron 9.71 x 10-8 6.41 x 10-3 1.03 x 107
Germanium1) 1 - 500 x 10-3 -50 x 10-3
Glass 1 - 10000 x 109
Gold 2.24 x 10-8
Iridium 5.3 x 10-8    
Iron 9.7 x 10-8    
Lead 20.6 x 10-8 0.45 x 107
Magnesium 4.45 x 10-8    
Manganese 185 x 10-8    
Mercury 98.4 x 10-8 8.9 x 10-3 0.10 x 107
Molybdenum 5.2 x 10-8    
Nickel 6.85 x 10-8 6.41 x 10-3
Nichrome (alloy of nickel and chromium) 0.40 x 10-3
Niobium (Columbium) 13 x 10-8    
Osmium 9 x 10-8    
Platinum 10.5 x 10-8 3.93 x 10-3 0.943 x 107
Plutonium 141.4 x 10-8    
Potassium 7.01 x 10-8    
Quartz
(fused)		 7.5 x 1017
Rhodium 4.6 x 10-8    
Rubber - hard 1 - 100 x 1013
Selenium 12.0 x 10-8    
Silicon1) 0.1-60 -70 x 10-3
Silver 1.59 x 10-8 6.1 x 10-3 6.29 x 107
Sodium 4.2 x 10-8    
Tantalum 12.4 x 10-8    
Thorium 18 x 10-8    
Tin 11.0 x 10-8    
Titanium 43 x 10-8    
Tungsten 5.65 x 10-8 4.5 x 10-3 1.79 x 107
Uranium 30 x 10-8    
Vanadium 25 x 10-8    
Zinc 5.92 x 10-8    

1) The resistivity depends strongly on the presence of impurities in the material

2) Resistivity and Temperature Coefficients at 20oC reference

Resistivity

The electrical resistance of a wire is greater for a longer wire and less for a wire of larger cross sectional area. The resistance depend on the material of which it is made and can be expressed as:

R = ρ L / A         (1)

where

R = resistance (ohm)

ρ = resistivity coefficient (ohm m)

L = length of wire (m)

A = cross sectional area of wire (m2)

The factor in the resistance which takes into account the nature of the material is the resistivity. Since it is temperature dependent, it can be used to calculate the resistance of a wire of given geometry at different temperatures.

Conductivity

The inverse of resistivity is called conductivity and can be expressed as:

σ = 1 / ρ         (2)

where

σ = conductivity (1 / Ω m)

Resistance

The electrical resistance of a circuit component or device is defined as the ratio of the voltage applied to the electric current which flows through it:

R = V / I         (3)

where

R = resistance (ohm)

V = voltage (V)

I = current (A)

Ohm's Law

If the resistance is constant over a considerable range of voltage, then Ohm's law,

I = V / R         (4)

can be used to predict the behavior of the material.

Temperature Coefficient

The electrical resistance increases with temperature. An intuitive approach to temperature dependence leads one to expect a fractional change in resistance which is proportional to the temperature change:

dR / Rs = α dT         (5)

where

dR = change in resistance (ohm)

Rs = standard resistance according reference tables (ohm)

α = temperature coefficient of resistance

dT = change in temperature (K)

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