Which is an example of heat transfer by radiation?

• A. Conduction through a metal spoon
• B. Convection currents in air
• C. Heating from the Sun through space
• D. Boiling kettle steam

Answer: (C)

Radiation is heat transfer by electromagnetic waves, which can happen even through empty space. The Sun warms Earth by sending energy through the vacuum of space as light and other waves, so it doesn’t need air or any material to carry the heat. That makes heating from the Sun through space a textbook example of radiation.

Conduction requires direct contact with something hot, as energy moves through a solid by particle interactions, like a metal spoon warming when it touches hot coffee. Convection involves the movement of a fluid; warm air or water rises and cooler portions sink, carrying heat with the moving fluid. Boiling kettle steam transfers energy mainly through the steam itself and fluid movement, involving phase changes and convection rather than electromagnetic waves.