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Resistivity and Conductivity - Temperature Coefficients Common Materials

Resistivity, conductivity and temperature coefficients for common materials like silver, gold, platinum, iron and more..

Resistivity is

• the electrical resistance of a unit cube of a material measured between the opposite faces of the cube

Electric Conductor Resistance Calculator

This calculator can be used to calculate electrical resistance of a conductor.

Resistivity Coefficient (ohm m) (default value for copper)

Cross sectional area of the conductor (mm2) - AWG Wire Gauge

MaterialResistivity Coefficient 2)
- ρ -
(ohm m2/m)
(Ω m)
Temperature
Coefficient
2)
- α  -

(per degree C)
(1/oC)
Conductivity
- σ -
(1 /(Ω m))
Aluminum 2.65 x 10-8 3.8 x 10-3 3.77 x 107
Aluminum alloy 3003, rolled 3.7 x 10-8
Aluminum alloy 2014, annealed 3.4 x 10-8
Aluminum alloy 360 7.5 x 10-8
Aluminum bronze 12 x 10-8
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
Beryllium copper 25 7 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
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
Cupronickel 55-45 (constantan) 43 x 10-8
Dysprosium (0oC) 89 x 10-8
Erbium (0oC) 81 x 10-8
Eureka   0.1 x 10-3
Europium (0oC) 89 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
Hastelloy C 125 x 10-8
Holmium (0oC) 90 x 10-8
Indium (3.35K) 8 x 10-8
Inconel 103 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
Magnesium alloy AZ31B 9 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 (Glimmer) 1 x 1013
Mild steel 15 x 10-8 6.6 x 10-3
Molybdenum 5.2 x 10-8
Monel 58 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
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
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.

Convert between Electrical Resistivity Units

• 1 Ω m = 10-2 Ω cm = 2.54 10-2 Ω inch = 3.048 10-1 Ω foot

Electrical Resistance in a Wire

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 Wire

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 = U / I                    (3)

where

R = resistance (ohm)

U = voltage (V)

I = current (A)

Ohm's Law

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

I = U / R                  (4)

can be used to predict the behavior of the material.

Resistivity vs. Temperature

Change in resistivity vs. temperature can be calculated as

= ρ α dt                  (5)

where

dρ = change in resistivity (ohm m2/m)

α = temperature coefficient (1/oC)

dt = change in temperature (oC)

Example - Change in Resistivity

Aluminum with resistivity 2.65 x 10-8 ohm m2/m is heated from 20 oC to 100 oC. The temperature coefficient for aluminum is 3.8 x 10-3 1/oC. The change in resistivity can be calculated as

dρ = (2.65 10-8 ohm m2/m) (3.8 10-3 1/oC) ((100 oC) - (20 oC))

= 0.8 10-8 ohm m2/m

The final resistivity can be calculated as

ρ = (2.65 10-8 ohm m2/m) + (0.8 10-8 ohm m2/m)

= 3.45 10-8 ohm m2/m

Resistivity Coefficient vs. Temperature Calculator

This caculator can be used to calculate resistivity in a conductor material vs. temperature.

ρ - resistivity coefficient (10-8 ohm m2/m)

α - temperature coefficient (10-3 1/oC)

dt - change in temperature (oC)

Resistance and Temperature

For most materials the electrical resistance increases with temperature. Change in resistance can be expressed as

dR / Rs = α dT                    (6)

where

dR = change in resistance (ohm)

Rs = standard resistance according reference tables (ohm)

α = temperature coefficient of resistance (oC-1)

dT = change in temperature from reference temperature (oC, K)

(5) can be modified to:

dR = α dT Rs                  (6b)

The "temperature coefficient of resistance" - α  - of a material is the increase in the resistance of a 1 Ω resistor of that material when the temperature is increased 1 oC

Example - Resistance of a Copper Wire in Hot Weather

A copper wire with resistance 0.5 kΩ at normal operating temperature 20oC is in hot sunny weather heated to 80 oC. The temperature coefficient for copper is 4.29 x 10-3 (1/oC) and  the change in resistance can be calculated as

dR = (4.29 x 10-3 1/oC) ((80 oC) - (20 oC)) (0.5 kΩ)

= 0.13 (kΩ)

The resulting resistance for the copper wire in hot weather will be

R = (0.5 kΩ) + (0.13 kΩ)

= 0.63 (kΩ)

= 630 (Ω)

Example - Resistance of a Carbon Resistor when Temperature is changed

A carbon resistor with resistance 1 kΩ at temperature 20oC is heated to 120 oC. The temperature coefficient for carbon is negative -4.8 x 10-4 (1/oC) - the resistance is reduced with increasing temperature.

The change in resistance can be calculated as

dR = (-4.8 x 10-4 1/oC) ((120 oC) - (20 oC)) (1 kΩ)

= - 0.048 (kΩ)

The resulting resistance for the resistor will be

R = (1 kΩ) - (0.048 kΩ)

= 0.952 (kΩ)

= 952 (Ω)

Resistance vs. Temperature Calculator

This caculator can be used to calculate resistance in a conductor vs. temperature.

Rs - resistance (103 (ohm)

α - temperature coefficient (10-3 1/oC)

dt - change in temperature (oC)

Temperature Correction Factors for Conductor Resistance

Temperature of Conductor
(°C)
Factor to Convert to 20°CReciprocal to Convert from 20°C
5 1.064 0.940
6 1.059 0.944
7 1.055 0.948
8 1.050 0.952
9 1.046 0.956
10 1.042 0.960
11 1.037 0.964
12 1.033 0.968
13 1.029 0.972
14 1.025 0.976
15 1.020 0.980
16 1.016 0.984
17 1.012 0.988
18 1.008 0.992
19 1.004 0.996
20 1.000 1.000
21 0.996 1.004
22 0.992 1.008
23 0.988 1.012
24 0.984 1.016
25 0.980 1.020
26 0.977 1.024
27 0.973 1.028
28 0.969 1.032
29 0.965 1.036
30 0.962 1.040
31 0.958 1.044
32 0.954 1.048
33 0.951 1.052

Related Topics

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

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Temperature

oC
oF

Length

m
km
in
ft
yards
miles
naut miles

Area

m2
km2
in2
ft2
miles2
acres

Volume

m3
liters
in3
ft3
us gal

Weight

kgf
N
lbf

Velocity

m/s
km/h
ft/min
ft/s
mph
knots

Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O

Flow

m3/s
m3/h
US gpm
cfm

3 10