Which mechanism involves transfer of heat by infrared waves from a warm surface to the surroundings without touching?

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

Answer: (A)

Heat transfer by infrared waves from a warm surface to the surroundings without touching is radiation. This uses electromagnetic waves that can travel through air or even vacuum, so energy moves from the hot object to cooler surroundings without contact. You feel this warmth from the sun, a campfire, or a heater lamp even when you’re not touching the source. Conduction needs direct touch, like a pot warming your hand. Convection involves moving the surrounding fluid (air or water) carrying heat with it. Evaporation involves a liquid turning into vapor, which cools the surface as energy is carried away. Radiation best fits the description.