Infrared radiation is primarily associated with which property?

• A. Radiation with wavelengths shorter than visible light
• B. Radiation that generates heat
• C. Radiation that causes DNA mutations
• D. Radiation at visible wavelengths only

Answer: (B)

Infrared radiation is the part of the spectrum with wavelengths just longer than visible light, and it is best understood as the energy associated with heat. Objects at everyday temperatures emit infrared photons as a natural part of thermal radiation, so infrared is strongly tied to warming. When infrared energy is absorbed by matter, it increases molecular vibrations and rotations, which we experience as heat. Its photons have less energy than those of visible or UV light, so infrared is not capable of ionizing atoms or causing the DNA damage associated with higher-energy radiation. That’s why infrared is described primarily by its heat-generating effect.