Which heat transfer mechanism involves direct contact causing heat to flow through solids?

Which heat transfer mechanism involves direct contact causing heat to flow through solids?

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

Answer: (A)

Heat transfer by direct contact through solids is conduction. In this mode, energy moves from the hotter region to the cooler region when two objects touch or when a solid contains a temperature gradient. In solids, energy is carried by vibrating atoms and, in metals, by free electrons that rapidly transfer kinetic energy across the material or at interfaces. This is different from convection, which requires moving fluids to carry heat, radiation, which transfers energy via electromagnetic waves without needing contact, and evaporation, which involves a phase change from liquid to vapor. Conduction is the mechanism that explains why a metal rod heats up along its length when one end is warmed, as the energy travels through the solid by particle interactions and electron movement.

Heat transfer by direct contact through solids is conduction. In this mode, energy moves from the hotter region to the cooler region when two objects touch or when a solid contains a temperature gradient. In solids, energy is carried by vibrating atoms and, in metals, by free electrons that rapidly transfer kinetic energy across the material or at interfaces. This is different from convection, which requires moving fluids to carry heat, radiation, which transfers energy via electromagnetic waves without needing contact, and evaporation, which involves a phase change from liquid to vapor. Conduction is the mechanism that explains why a metal rod heats up along its length when one end is warmed, as the energy travels through the solid by particle interactions and electron movement.