Which materials have high thermal conductivity?

• A. Plastics
• B. Ceramics
• C. Metals
• D. Wood

Answer: (C)

Heat moves through materials most efficiently when there are many free charge carriers that can carry energy quickly. In metals, a large number of free electrons move rapidly and shuttle thermal energy from hotter regions to cooler ones, making metals excellent heat conductors. Plastics and wood, on the other hand, are poor conductors because they have few free electrons and often contain air gaps, so heat must travel mainly through slower lattice vibrations and through air. Ceramics can be insulators as well, due to their bonding that limits free-charge movement, though some ceramics can conduct heat better than plastics. A practical example is metal cookware that heats quickly and evenly, while a wooden spoon stays relatively cool because wood doesn’t transfer heat as well. So metals are the materials with high thermal conductivity.