At what temperature is infrared radiation emitted from an object?

• A. 0 Kelvin
• B. Above 0 Kelvin
• C. Below 0 Kelvin
• D. Only above 100 Kelvin

Answer: (B)

Infrared radiation comes from the thermal motion of particles inside an object. Any object with a temperature above absolute zero emits some infrared energy. At 0 kelvin there would be no motion, so no radiation. In practice, even modestly warm objects (well above 0 K) radiate in the infrared, and hotter objects emit more energy and start peaking at shorter wavelengths within the infrared range. The idea that it only happens above a specific higher temperature, like 100 kelvin, isn’t correct because room-temperature objects and everyday warm bodies emit infrared as well.