The Effect of Temperature on Thermal Conductivity

Temperature affects thermal conductivity.

The atoms and molecules in all substances are moving -- either vibrating in solids or actually moving in liquids and gases. Temperature measures their average kinetic energy or energy of motion. Thermal conductivity changes with temperature.

Types

Thermal conductivity describes the rate at which a substance conducts heat. Metals are common examples of good heat conductors. Substances that conduct heat poorly, by contrast, are called insulators. Thermal conductivity is defined in units of watts per meter Kelvins, where Kelvins are a measure of temperature. To convert from degrees Celsius to Kelvins, add 273.15.

Effects

Thermal conductivity is relatively constant over a narrow temperature range. As the temperature increases, however, the rate at which particles in the substance are moving increases, and the rate at which heat is transferred typically increases as well.

Considerations

Metals are a common example of substances that transmit heat well. In metals, the thermal conductivity increases with temperature, while electrical conductivity decreases. The thermal conductivity for a metal divided by the electrical conductivity is equal to the temperature times L, where L is a constant equal to 2.45 times 10 to the -8 watts ohms divided by Kelvins squared.

References

• Georgia State University Hyperphysics: Thermal Conductivity and the Wiedemann-Franz Law
• University of Stuttgart: Temperature and Moisture Dependence of the Thermal Conductivity of Insulation Materials
• "Physics for Scientists and Engineers"; Richard Wolfson and Jay Pasachoff; 1999