Infrared radiation | Definition, Wavelengths, Facts | Britannica Infrared radiation, that portion of the electromagnetic spectrum that extends from the long wavelength, or red, end of the visible-light range to the microwave range Invisible to the eye, it can be detected as a sensation of warmth on the skin Learn more about infrared radiation in this article
What Is Infrared? - Live Science Infrared radiation is a type of electromagnetic radiation It is invisible to human eyes, but people can feel it as heat