The process by which heat is transferred in solid materials due to molecular interactions without bulk movement is called what?

• A. Radiation
• B. Conduction
• C. Convection
• D. Evaporation

Answer: (B)

Heat transfer through a solid arises from the direct interaction of particles within the material, without the material as a whole moving. In solids, hotter regions have particles that vibrate more vigorously and transfer energy to neighboring particles through collisions and interactions in the lattice. In metals, free electrons carry energy rapidly from the hotter area to a cooler area, helping conduction happen even faster. This is different from radiation, which uses electromagnetic waves to transfer energy through space, and from convection, which relies on the bulk movement of a fluid, and from evaporation, which involves a phase change. A practical example is touching a hot metal rod—the heat moves through the rod by conduction from the hotter end to the cooler end, even though the rod itself isn’t flowing.