Thermal Conductivity
Definition
How well a material conducts heat — high for metals, low for insulators like wood or foam.
Symbol: · Unit: W/(m·K)
Technical definition
The proportionality constant k in Fourier's law of heat conduction: q = −k∇T (heat flux proportional to temperature gradient). Units W/(m·K). Copper (~400) conducts ~10,000× better than air (~0.026).
Example
A metal spoon in hot soup burns your fingers while a wooden spoon stays cool — copper's conductivity (~400 W/m·K) dwarfs wood's (~0.1).
Common confusion
Cold-feeling metal is not colder than wood at room temperature — it just conducts heat away from your skin faster. ‘Feels cold’ measures heat flow rate, not temperature.