Which materials have high thermal conductivity?

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

Answer: (D)

Thermal conductivity describes how easily heat moves through a material. Metals conduct heat very efficiently because they have free electrons that move rapidly and can transfer energy from the hot region to the cooler region almost instantaneously. These electrons act like a highway for thermal energy, with collisions that spread heat quickly through the metal. The lattice vibrations help a bit, but the free-electron mechanism dominates metal’s ability to conduct heat.

Glass and ceramics, on the other hand, have strong bonds and few free electrons, so they rely mainly on slower lattice vibrations to transfer heat, making them poor conductors. Wood has a porous structure with many air pockets that further impede heat flow, also resulting in low thermal conductivity.

So metals stand out as having high thermal conductivity.