Heat transfer by direct contact with a solid object is known as which mechanism?

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

Answer: (A)

Direct contact heat transfer through touching is conduction. When two solids meet, heat flows from the hotter part to the cooler part by the interaction of particles at their interfaces. In metals, free electrons move quickly and shuttle energy from the hot region to the cooler region, while in nonmetals, vibrational energy travels through the lattice (phonons) to spread the heat. This mechanism requires physical contact, which is why it’s distinct from other modes: convection involves moving fluids that carry heat with their flow; radiation transmits energy as electromagnetic waves and can occur through space; evaporation is a phase change and not a direct transfer mechanism. So, the process described is conduction.