Direct transfer of heat through contact with a colder surface is called?

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

Answer: (A)

Conduction is heat transfer through direct contact between objects. When a warmer surface touches a colder one, energy moves from the hotter material to the cooler one through molecular collisions and lattice vibrations, warming the cooler object while cooling the warmer one until they reach similar temperatures. Metals conduct heat well because their electrons rapidly transfer energy, while insulators with trapped air slow this transfer. Other heat-transfer modes don’t require contact: radiation moves heat via electromagnetic waves (like the sun warming your skin), convection transfers heat through moving fluids or gases, and evaporation cools a surface as a liquid turns into vapor.