Which method of heat transfer occurs by electromagnetic waves and does not require matter?

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

Answer: (C)

Radiation is the way heat moves using electromagnetic waves, so it doesn’t need any matter to transfer energy. Any object above very cold temperatures emits some of this energy as infrared waves, which can travel through empty space and warm another object without touching it—like the Sun heating Earth.

Conduction needs contact between substances, with energy passed by particle collisions and vibrations. Convection depends on the movement of a fluid, carrying heat with circulating currents. Evaporation is a phase change where a liquid becomes vapor, which involves energy transfer but isn’t a separate mode of heat transfer like radiation.