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

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

Resistivity is the

  • resistance of a unit cube of the material measured between the opposite faces of the cube
MaterialResistivity Coefficient 2)
- ρ -
(ohm m)
Temperature
Coefficient
2)
(per degree C, 1/oC)
Conductivity
- σ -
(1 /Ωm)
Aluminum 2.65 x 10-8 3.8 x 10-3 3.77 x 107
Animal fat 14 x 10-2
Animal muscle 0.35
Antimony 41.8 x 10-8    
Barium (0oC) 30.2 x 10-8
Beryllium 4.0 x 10-8    
Bismuth 115 x 10-8    
Brass - 58% Cu 5.9 x 10-8 1.5 x 10-3
Brass - 63% Cu 7.1 x 10-8 1.5 x 10-3
Cadmium 7.4 x 10-8    
Caesium (0oC) 18.8 x 10-8
Calcium (0oC) 3.11 x 10-8
Carbon (graphite)1) 3 - 60 x 10-5 -4.8 x 10-4
Cast iron 100 x 10-8
Cerium (0oC) 73 x 10-8
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 3 x 10-5 0.20 x 107
Copper 1.724 x 10-8 4.29 x 10-3 5.95 x 107
Dysprosium (0oC) 89 x 10-8
Erbium (0oC) 81 x 10-8
Eureka   0.1 x 10-3  
Europium (0oC) 89 x 10-8
Gadolium 126 x 10-8
Gallium (1.1K) 13.6 x 10-8
Germanium1) 1 - 500 x 10-3 -50 x 10-3
Glass 1 - 10000 x 109 10-12
Gold 2.24 x 10-8
Graphite 800 x 10-8 -2.0 x 10-4
Hafnium (0.35K) 30.4 x 10-8
Holmium (0oC) 90 x 10-8
Indium (3.35K) 8 x 10-8
Iridium 5.3 x 10-8    
Iron 9.71 x 10-8 6.41 x 10-3 1.03 x 107
Lanthanum (4.71K) 54 x 10-8
Lead 20.6 x 10-8 0.45 x 107
Lithium 9.28 x 10-8
Lutetium 54 x 10-8
Magnesium 4.45 x 10-8    
Manganese 185 x 10-8 1.0 x 10-5  
Mercury 98.4 x 10-8 8.9 x 10-3 0.10 x 107
Mica 1 x 1013
Mild steel 15 x 10-8 6.6 x 10-3
Molybdenum 5.2 x 10-8    
Neodymium 61 x 10-8
Nichrome (alloy of nickel and chromium) 100 - 150 x 10-8 0.40 x 10-3
Nickel 6.85 x 10-8 6.41 x 10-3
Nickeline 50 x 10-8 2.3 x 10-4
Niobium (Columbium) 13 x 10-8    
Osmium 9 x 10-8    
Palladium 10.5 x 10-8
Phosphorus 1 x 1012
Platinum 10.5 x 10-8 3.93 x 10-3 0.943 x 107
Plutonium 141.4 x 10-8    
Polonium 40 x 10-8
Potassium 7.01 x 10-8    
Praseodymium 65 x 10-8
Promethium 50 x 10-8
Protactinium (1.4K) 17.7 x 10-8
Quartz (fused) 7.5 x 1017
Rhenium (1.7K) 17.2 x 10-8
Rhodium 4.6 x 10-8    
Rubber - hard 1 - 100 x 1013
Rubidium 11.5 x 10-8
Ruthenium (0.49K) 11.5 x 10-8
Samarium 91.4 x 10-8
Scandium 50.5 x 10-8
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    
Soil, typical ground 10-2 - 10-4
Solder 15 x 10-8
Stainless steel 106
Strontium 12.3 x 10-8
Sulfur 1 x 1017
Tantalum 12.4 x 10-8    
Terbium 113 x 10-8
Thallium (2.37K) 15 x 10-8
Thorium 18 x 10-8    
Thulium 67 x 10-8
Tin 11.0 x 10-8  4.2 x 10-3  
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    
Water, distilled 10-4
Water, fresh 10-2
Water, salt 4
Ytterbium 27.7 x 10-8
Yttrium 55 x 10-8
Zinc 5.92 x 10-8  3.7 x 10-3  
Zirconium (0.55K) 38.8 x 10-8

1) Note! - the resistivity depends strongly on the presence of impurities in the material.

2) Note! - the resistivity depends strongly on the temperature of the material. The table above is based on 20oC reference.

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, Ω)

ρ = resistivity coefficient (ohm m, Ω 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.

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

σ = 1 / ρ         (2)

where

σ = conductivity (1 / Ω m)

Example - Resistance in an Aluminum Cable

Resistance of an aluminum cable with length 10 m and cross sectional area of 3 mm2 can be calculated as

R = (2.65 10-8 Ω m) (10 m) / ((3 mm2) (10-6 m2/mm2))

   = 0.09 Ω

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 of Resistance

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)

(5) can be modified to:

dR = α dT Rs   (5b)

Example - Resistance of a Carbon resistor when changing Temperature

A carbon resistor with resistance 1 kΩ is heated 100 oC. With a temperature coefficient -4.8 x 10-4 (1/oC) the resistance change can be calculated as

dR = (-4.8 x 10-4 1/oC) (100 oC) (1 kΩ)

    = - 0.048 (kΩ)

The resulting resistance for the resistor

R = (1 kΩ) - (0.048 kΩ)

    = 0.952 (kΩ)

    = 952 (Ω)

Related Topics

  • Electrical - Amps and electrical wiring, AWG - wire gauge, electrical formulas, motors and units

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