This is a table of the electrical resistivity and electrical conductivity of several materials. Included are metals, elements, water, and insulators.
Electrical resistivity, represented by the Greek letter ρ (rho), is a measure of how strongly a material opposes the flow of electric current. The lower the resistivity, the more readily the material permits the flow of electric charge. The higher the resistivity, the harder it is for current to flow. Materials with high resistivity are electrical resistors.
Electrical conductivity is the reciprocal quantity of resistivity. Conductivity is a measure of how well a material conducts an electric current. Materials with high electrical conductivity are electrical conductors. Electric conductivity may be represented by the Greek letter σ (sigma), κ (kappa), or γ (gamma).
Table of Resistivity and Conductivity at 20°C
|Material||ρ (Ω•m) at 20 °C|
|σ (S/m) at 20 °C|
|Grain oriented electrical steel||4.60×10−7||2.17×106|
|GaAs||5×10−7 to 10×10−3||5×10−8 to 103|
|Carbon (amorphous)||5×10−4 to 8×10−4||1.25 to 2×103|
|Carbon (graphite)||2.5×10−6 to 5.0×10−6 //basal plane|
3.0×10−3 ⊥basal plane
|2 to 3×105 //basal plane|
3.3×102 ⊥basal plane
|Drinking water||2×101 to 2×103||5×10−4 to 5×10−2|
|Wood (damp)||1×103 to 4||10−4 to 10-3|
|Glass||10×1010 to 10×1014||10−11 to 10−15|
|Wood (oven dry)||1×1014 to 16||10−16 to 10-14|
|Air||1.3×1016 to 3.3×1016||3×10−15 to 8×10−15|
|Teflon||10×1022 to 10×1024||10−25 to 10−23|
Factors That Affect Electrical Conductivity
There are three main factors that affect the conductivity or resistivity of a material:
- Cross-Sectional Area: If the cross-section of a material is large, it can allow more current to pass through it. Similarly, a thin cross-section restricts current flow. For example, a thick wire has a higher cross-section than a fine wire.
- Length of the Conductor: A short conductor allows current to flow at a higher rate than a long conductor. It’s sort of like trying to move a lot of people through a hallway compared with a door.
- Temperature: Increasing temperature makes particles vibrate or move more. Increasing this movement (increasing temperature) decreases conductivity because the molecules are more likely to get in the way of current flow. At extremely low temperatures, some materials are superconductors.
- Glenn Elert (ed.). “Resistivity of steel.” The Physics Factbook.
- MatWeb Material Property Data.
- Ohring, Milton (1995). Engineering materials science, Volume 1 (3rd ed.). p. 561.
- Pawar, S. D.; Murugavel, P.; Lal, D. M. (2009). “Effect of relative humidity and sea level pressure on electrical conductivity of air over Indian Ocean”. Journal of Geophysical Research 114: D02205.