Transfer of radiant heat, such as entering a walk-in freezer, is called?

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

Answer: (C)

Radiant heat transfer is heat moving through electromagnetic waves, mainly infrared, and it doesn’t need contact or a moving medium. When you step into a walk-in freezer, the surrounding walls and surfaces are much colder than your body. They emit infrared energy toward you, and your warm body absorbs some of that energy while also losing heat to the colder surfaces. This is why you feel cold even before any air movement or direct contact with the cold air. Conduction would require touching a surface, convection involves heat carried by moving air, and evaporation involves a liquid changing to vapor—none of those describe the direct transfer of heat by radiation.