Infrared radiation is emitted by which of the following?

• A. Everything with a temperature
• B. Only living things
• C. Only metals
• D. Only objects heated to extremes

Answer: (A)

Infrared radiation comes from thermal energy produced by any object that has a temperature. When an object is above absolute zero, its molecules are in motion and emit electromagnetic radiation across a range of wavelengths. The distribution of this radiation follows Planck’s law, and for everyday temperatures the peak falls in the infrared region, which is why you can detect heat from walls, furniture, and people with infrared instruments even though you can’t see it with the naked eye. This means infrared emission is not exclusive to living things; metals and other non-living objects also emit infrared. The idea that only objects heated to extremes emit infrared is too limited, because ordinary objects at typical temperatures already radiate infrared energy.