Which method of heat transfer occurs through direct contact, typically in solids?

The method of heat transfer that occurs through direct contact, particularly in solids, is conduction. This process involves the transfer of thermal energy from one particle to another within a material without any movement of the material as a whole. In solids, conduction is most efficient because the particles are closely packed together, allowing them to collide and transfer kinetic energy directly.

For instance, when a metal rod is heated at one end, the heat travels through the rod to the cooler end. The molecules at the heated end gain energy and vibrate more vigorously, passing that energy to adjacent, cooler molecules through direct contact. This mechanism is distinctly different from convection, which involves the movement of fluids (liquids and gases), and radiation, which involves heat transfer through electromagnetic waves without requiring a medium. Advection refers to the transport of heat or cold as a result of fluid flow, further emphasizing the unique nature of conduction as the only mode involving direct molecular interactions in solids.