What does conduction refer to in the context of heat transfer?

Conduction in the context of heat transfer specifically refers to the process where heat energy is transferred through direct contact between materials. When two objects at different temperatures come into contact, heat flows from the hotter object to the cooler one until thermal equilibrium is reached. This occurs at a molecular level where faster-moving molecules in the hotter object transfer kinetic energy to slower-moving molecules in the cooler object upon collision.

This understanding is fundamental in various applications, from cooking to engineering, as it helps predict how heat will move through different materials. In contrast, the other options reflect different mechanisms of heat transfer: radiation involves energy transfer in the form of electromagnetic waves and does not require direct contact; convection refers to heat transfer through the movement of fluids (liquids or gases); and energy transfer without physical contact typically describes radiation again, not conduction. Hence, recognizing conduction as direct contact is essential for distinguishing it from other heat transfer methods.