What does thermal conductivity measure?

• A. The ability of a material to transport heat
• B. The amount of heat stored per unit mass
• C. The rate of chemical reaction
• D. The heat capacity at constant pressure

Answer: (A)

Thermal conductivity measures how readily heat can move through a material when there is a temperature difference across it. It is the proportionality constant in Fourier's law, linking heat flux to the temperature gradient. A material with high conductivity allows heat to flow quickly (like metals), while a material with low conductivity resists heat flow (like wood or plastic). The other options describe how much energy is needed to raise the temperature (specific heat or heat capacity) or the rate of a chemical reaction, which are not about how fast heat is transported. So the best description is the material’s ability to transport heat.