There are aspects of the electromagnetic spectrum the human eye can’t see. This consists of thermal infrared radiation. This really is radiation with long wavelengths. Every thing emits thermal radiation - even human beings. Objects like a stove element on substantial, emit radiation from the noticeable spectrum when it glows https://brooksghzly.answerblogs.com/30607198/considerations-to-know-about-hand-held-thermal-imagers