What does conduction refer to in terms of heat transfer?

Conduction refers specifically to the transfer of heat through direct contact between materials. When two objects at different temperatures come into contact with each other, heat moves from the hotter object to the cooler one until thermal equilibrium is reached. This process occurs at a molecular level, where faster-moving molecules collide with slower-moving ones, transferring kinetic energy and thereby increasing the temperature of the cooler material.

The other options describe different modes of heat transfer. Heat transfer through air involves convection, where heat is carried away by fluid movement, typically in liquids or gases. Radiation refers to the emission of energy in the form of electromagnetic waves, which can occur even in a vacuum where no medium is present. Heat movement in a vacuum also relates to radiation since there is no medium for conduction or convection to occur. Understanding these distinctions is crucial for grasping how heat is transferred in various contexts.