The process by which heat is exchanged through the emission of photons, without requiring matter, is known as what?

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

Answer: (B)

Heat transfer via electromagnetic waves carried by photons does not require any matter to mediate the transfer. This is radiation, which can carry energy through empty space, as when sunlight warms the Earth. Conduction, by contrast, needs direct contact and transfers energy through molecular interactions or electron movement within a substance. Convection relies on the bulk movement of a fluid to transport heat. Evaporation involves a phase change and is a way energy can move as liquids turn to vapor, but it’s not the general mechanism for transferring heat across a distance. Therefore, the process described is radiation.