What are the three types of heat transfer?

• A. Conduction, convection, radiation
• B. Conduction, convection, evaporation
• C. Radiation, convection, conduction
• D. Evaporation, conduction, convection

Answer: (A)

Heat moves by three fundamental mechanisms: conduction, convection, and radiation. Conduction happens through direct contact and molecular interactions—energy flows from hotter to cooler parts, like a metal spoon warming when placed in hot soup. Convection occurs in liquids and gases when warmer, lighter regions rise and cooler, denser regions sink, creating circulating currents, as seen when air warms from a heater or water boils in a pot. Radiation is energy transfer through electromagnetic waves and can occur without any material medium, such as the sun warming the earth or heat from a fire felt at a distance. Evaporation involves a phase change and can accompany heat transfer, but the three basic modes describing how heat moves are conduction, convection, and radiation.