Microwaving popcorn uses which type of heat transfer?

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

Answer: (C)

Microwaving popcorn heats primarily through radiation—microwave energy that travels into the kernels and directly excites water and other molecules inside. This energy is absorbed from a distance, warming the interior rather than relying on contact with a hot surface or on moving hot air. As the water inside turns to steam, pressure builds until the kernel bursts open, which is why popcorn pops. Conduction would require touching a hot surface, and convection would involve heated air circulating to transfer heat, neither of which is the main mechanism in a microwave. Evaporation describes a phase change, not how heat is transferred.