The body gives off heat in waves from uncovered surfaces. Which heat transfer mechanism is this?

• A. Radiation
• B. Conduction
• C. Convection
• D. Evaporation

Answer: (A)

Heat transfer by waves from uncovered surfaces is radiation. Radiation is the emission of energy as electromagnetic waves, which can travel through air or even through space without a medium. The body naturally radiates infrared energy as its temperature rises. This differs from conduction, which requires direct contact to pass energy through a solid, and convection, which involves heat carried by moving fluids like air or water, and evaporation, which involves a liquid changing to vapor and removing heat. The clue here is the use of waves, pointing to radiation.