Conduction can refer to either:
- Thermal conduction: the physical property of heat moving through material
- Electrical conduction: the physical property of electricity moving through material
The word conductor usually means a material with high electrical conductivity (low resistivity). However, most electric conductors (usually metals), are good thermal conductors as well. For example, copper is both an excellent thermal conductor and electrical conductor. A simple model that explains this relationship (a good conceptual model, but it skips some important details) is pretending that the electrons in the metal behave like a gas that are free to move and carry both electric current and heat.
Ratio of Thermal to Electrical Conductivity
The values for thermal conductivity and electrical conductivity for many metals depend on temperature. The higher the temperature the greater the thermal conduction (compared to electrical conduction). This linear relationship can be expressed and compared using a ratio known as the Wiedemann-Franz law. This ratio is expressed as:
- is a constant known as the Lorentz number, equal to
- is the thermal conductivity of the material
- electrical conductivity of the material is the
- is the temperature of the material, in Kelvin
- Boltzmann's constant is the
- electron is the elementary charge of an
The reverse is usually but not always true; for example, diamonds are excellent thermal conductors (even better than copper) but usually electrical insulators. Although at very low temperatures a research group found  showing that diamonds can become superconductors below 4 K (superconductivity is specifically a description of electrical conduction, not thermal conduction).
For Further Reading
- Thermal conduction
- Electrical conduction
- Fibrous insulation
- Or explore a random page
- Pixabay. (2013). Copper-wire [Online]. Available: http://pixabay.com/p-113249/?no_redirect.
- Boston University. (1998). Heat Transfer, and The First Law of Thermodynamic [Online]. Available: http://physics.bu.edu/~duffy/py105/notes/Heattransfer.html
- Virginia Universiy. Electrical Conduction [Online]. Available: http://www.virginia.edu/bohr/mse209/chapter19.htm
- Electronics Cooling. (2000). How Thermal Conductivity Relates to Electrical Conductivity [Online]. Available: http://www.electronics-cooling.com/2000/05/how-thermal-conductivity-relates-to-electrical-conductivity/
- HyperPhysics. (May 12, 2015). Thermal Conductivity [Online]. Available: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thercond.html
- Ekimov et al., "Superconductivity in diamond" in Nature, Vol. 428, New York: MacMillan, 2004, pp. 542-5. Available: http://www.nims.go.jp/NFM/paper1/SuperconductingDiamond/01nature02449.pdf