Heat is transferred usually through the air from a warmer source to a cooler source. Which mode is this?

Heat is transferred usually through the air from a warmer source to a cooler source. Which mode is this?

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

Answer: (D)

Radiation is the transfer of heat by electromagnetic waves. These waves can travel through air (or even through a vacuum) from a warmer object to a cooler one without needing any contact or moving air. Feel the warmth from a distant heater or the sun because radiant heat travels through the surrounding air. Conduction needs touch, and convection relies on the bulk movement of air to carry heat, while evaporation involves a phase-change process that absorbs heat. So heat moving through air from a warmer source to a cooler area without contact is best explained by radiation.

Radiation is the transfer of heat by electromagnetic waves. These waves can travel through air (or even through a vacuum) from a warmer object to a cooler one without needing any contact or moving air. Feel the warmth from a distant heater or the sun because radiant heat travels through the surrounding air. Conduction needs touch, and convection relies on the bulk movement of air to carry heat, while evaporation involves a phase-change process that absorbs heat. So heat moving through air from a warmer source to a cooler area without contact is best explained by radiation.