What are three methods of heat transfer?

• A. Conduction, convection, and radiation.
• B. Reflection, conduction, and absorption.
• C. Radiation, reflection, and convection.
• D. Conduction, radiation, and evaporation.

Answer: (A)

Heat moves in three fundamental ways: conduction, convection, and radiation. Conduction is heat transfer through a solid or between touching bodies, driven by molecular interactions; for example, a hot engine part warming a nearby bracket through direct contact. Convection involves the movement of a fluid—air or coolant—carrying heat as the warmer, less dense portion rises and cooler portions take its place; this happens as air flows over a hot surface or as coolant circulates in a system. Radiation is heat transferred by electromagnetic waves and does not require a medium, so a hot surface can warm objects farther away or even heat through space.

These three modes cover how heat travels in most aerospace scenarios, whether through a heated component, the surrounding air, or via radiant heat from a hot surface. Other terms like reflection or absorption relate to light behavior rather than a distinct heat-transfer mechanism, and evaporation is a phase-change process that involves heat but isn’t one of the primary transfer modes.