Which statement describes how radiation moves?

Which statement describes how radiation moves?

• A. Radiation moves from a cooler object to a warmer object
• B. Radiation moves from a warmer object to an object of the same temperature
• C. Radiation moves from a warm object to an object at a different temperature
• D. Radiation moves from a warmer object to a cooler object

Answer: (D)

Radiation is heat transfer through electromagnetic waves and doesn’t need a medium. When two objects have different temperatures, the hotter object emits more radiant energy than the cooler one, so the net transfer of energy goes from the warmer object to the cooler object. That explicit direction—warmer to cooler—best describes how radiation moves. If the temperatures are the same, there is no net transfer by radiation. Saying radiation moves from a warm object to an object at a different temperature can be true in general, but it doesn’t specify which object is hotter, so it’s incomplete. The clear, correct idea is that heat via radiation flows from the warmer to the cooler object.

Radiation is heat transfer through electromagnetic waves and doesn’t need a medium. When two objects have different temperatures, the hotter object emits more radiant energy than the cooler one, so the net transfer of energy goes from the warmer object to the cooler object. That explicit direction—warmer to cooler—best describes how radiation moves.

If the temperatures are the same, there is no net transfer by radiation. Saying radiation moves from a warm object to an object at a different temperature can be true in general, but it doesn’t specify which object is hotter, so it’s incomplete. The clear, correct idea is that heat via radiation flows from the warmer to the cooler object.