Table of resistivity and conductivity
Description
A reference guide for electrical resistivity and conductivity of materials at different temperatures, based on IEC standards.
"Calculation of the resistivity and conductivity of a material based on temperature. Resistivity strongly depends on the presence of impurities in the material. Copper resistivity according to IEC 60028, aluminium resistivity according to IEC 60889."
Parameters
Resistivity
Electrical resistivity is a fundamental property of a material that measures how strongly it resists electric current.
Conductivity
Electrical conductivity is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current.
Temperature coeff.
Temperature coefficient of resistance for the conductor material.
Temperature Dependence Formula
ρ(T) = ρ₀ [1 + α (T - T₀)]
Where:
- ρ(T): Resistivity at temperature T
- ρ₀: Resistivity at reference temperature T₀ (20°C)
- α: Temperature coefficient of resistance (°C⁻¹)
- T: Operating temperature in °C
Standard Values (IEC 60028, IEC 60889)
| Material | Resistivity @ 20°C (Ω·m) | Conductivity (S/m) | α (°C⁻¹) | Standard |
|---|---|---|---|---|
| Copper (Cu) | 1.724 × 10⁻⁸ | 5.796 × 10⁷ | 0.00393 | IEC 60028 |
| Aluminum (Al) | 2.828 × 10⁻⁸ | 3.536 × 10⁷ | 0.00403 | IEC 60889 |
| Silver (Ag) | 1.587 × 10⁻⁸ | 6.300 × 10⁷ | 0.0038 | – |
| Gold (Au) | 2.44 × 10⁻⁸ | 4.10 × 10⁷ | 0.0034 | – |
| Iron (Fe) | 9.7 × 10⁻⁸ | 1.03 × 10⁷ | 0.005 | – |
Why Impurities Matter
Even small amounts of impurities can increase resistivity by up to 20%. For example:
- Pure copper: ~1.724 × 10⁻⁸ Ω·m
- Commercial copper: up to 20% higher
Use high-purity copper for precision applications like power transmission lines.
Practical Use Cases
- Power Line Design: Calculate voltage drop and select wire size
- Motor Windings: Estimate resistance at operating temperature
- PCB Traces: Model thermal behavior and signal loss
- Sensors: Calibrate RTDs and compensate for temperature drift
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