Which of the following is NOT a method of heat transfer?

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

Answer: (D)

Heat moves in three recognized ways: conduction through direct contact where energy passes from molecule to molecule; convection in fluids where currents circulate heated portions and carry energy with them; and radiation, which is energy traveling as electromagnetic waves that can transfer heat without a medium. Adhesion is not a mechanism of heat transfer—it’s the attraction between different substances’ surfaces, influencing sticking or wetting rather than moving thermal energy. In practical terms, you’d see heat traveling from a hot surface to a cooler one by conduction, from a flame heating surrounding air by convection, or heat radiating from a hot object to farther surfaces by radiation; adhesion affects how surfaces stay together, not how heat is transported between them.