Which term describes the measure of how fast heat is conducted through a material when there is a temperature difference across it?

• A. Thermal conductivity
• B. Thermo-electricity
• C. Toughness
• D. Volume

Answer: (A)

Thermal conductivity describes how readily heat travels through a material when there is a temperature difference across it. It’s the property that determines how quickly heat will move from the hotter side to the cooler side for a given thickness and gradient. In practical terms, a material with high thermal conductivity, like copper, conducts heat quickly, while a material with low thermal conductivity, like wood or plastic, acts as an insulator and slows heat flow. The concept is captured by Fourier’s law, where the heat flux is proportional to the temperature gradient with the proportionality constant being the thermal conductivity. This is typically expressed in units of watts per meter per kelvin (W/m·K). The other terms relate to different ideas: thermo-electricity concerns converting heat differences into electrical energy, toughness relates to resistance to fracture, and volume is a measure of the space a material occupies.