Custom Search
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
Sponsored Links
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.
| 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 |
| Animal muscle | 0.35 | ||
| Animal fat | 14 x 10-2 | ||
| Antimony | 41.8 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 | ||
| Carbon (graphite)1) | 3 - 60 x 10-5 | -4.8 x 10-4 | |
| Cast iron | 100 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 |
| 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 | 10-12 | |
| Gold | 2.24 x 10-8 | ||
| Graphite | 800 x 10-8 | -2.0 x 10-4 | |
| 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 | 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 | ||
| Nickel | 6.85 x 10-8 | 6.41 x 10-3 | |
| Nickeline | 50 x 10-8 | 2.3 x 10-4 | |
| Nichrome (alloy of nickel and chromium) | 100 - 150 x 10-8 | 0.40 x 10-3 | |
| Niobium (Columbium) | 13 x 10-8 | ||
| Osmium | 9 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 | ||
| 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 | ||
| Soil, typical ground | 10-2 - 10-4 | ||
| Stainless steel | 106 | ||
| Sulfur | 1 x 1017 | ||
| Tantalum | 12.4 x 10-8 | ||
| Thorium | 18 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 | ||
| Zinc | 5.92 x 10-8 | 3.7 x 10-3 |
1) The resistivity depends strongly on the presence of impurities in the material
2) Resistivity and Temperature Coefficients at 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 / 1000000 (mm2/m2)
= 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)
Sponsored Links
Search the Engineering ToolBox
Custom Search
Engineering ToolBox - SketchUp Edition - Online 3D modeling!
Engineering ToolBox - SketchUp Edition - enabled for use with the amazing, fun and free Google SketchUp