Radiation is defined as what?

• A. Absorption of energy by chemical bonds
• B. Transfer of energy as an electromagnetic wave
• C. Transfer of heat by convection
• D. Transmission of energy as an electromagnetic wave, light waves, radio waves

Answer: (D)

Radiation means energy moving through space by electromagnetic waves. It doesn’t need a medium to travel, so it can move through vacuum, which is why sunlight reaches Earth. This is different from conduction (energy transfer by direct contact) and convection (energy transfer by moving fluids). In a fire, radiant heat from flames can heat objects at a distance without touching them, which is a key reason radiant heat is a major factor in fire spread and ignition. The option describing energy transfer as an electromagnetic wave (and including light and radio waves as examples) best captures this concept.