Heat transfer by direct contact between surfaces is called?

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

Answer: (A)

Heat transfer by direct contact between surfaces is conduction. This happens when two objects touch and energy is passed from the more energetic molecules to the less energetic ones through molecular interactions and collisions. In solids, the close contact and, in metals, the presence of free electrons make it an efficient form of heat transfer. A common example is touching a hot stove and feeling heat move into your skin. In the body, conduction occurs when the skin or tissues touch something at a different temperature, transferring heat to or from the surface in contact. The other modes rely on different mechanisms: convection requires movement of a fluid to carry heat, radiation transfers energy via electromagnetic waves without contact, and evaporation involves a liquid changing to vapor with heat uptake or loss.