NOCTI Pre-Engineering Practice Exam

Heat conduction is the transfer of thermal energy within a material or between materials that are in direct contact, driven by a temperature difference. The speed of that transfer is governed by a property called thermal conductivity. A material with high thermal conductivity allows energy to move quickly from the hotter part to the cooler part, so it conducts heat readily. In metals, free electrons act as fast energy carriers, making conduction especially efficient; in nonmetals, energy moves mainly through lattice vibrations (phonons) and is less efficient. Vacuum cannot conduct heat because there are no particles to transfer energy by collisions, though heat can still be transferred by radiation. Insulators have low thermal conductivity and resist heat flow, while not all liquids are perfect conductors—many conduct heat poorly, though some vary in conductivity. So the statement that describes heat conduction best is that materials with high thermal conductivity conduct heat readily.