Answer: Infrared radiation
Explanation:
Infrared radiation is not visible to the human eye, since its wavelengths are outside the visible spectrum (between 700 nm and 1 mm), however this type of electromagnetic radiation is detected by the human body as heat.
These waves can be divided into:
- Near infrared or long wave infrared: it is the least sensitive to color and is easily absorbed by water.
- Medium or medium wave infrared: it is also insensitive to color and easily absorbed by water and many types of plastics and paints.
- Far infrared or short wave infrared: it is more penetrating than the long wave and is good for heating metals, these waves also can pass through clear materials. This light has many uses, including heating lamps in physiotherapy and medical treatments, heat sensing devices, among others.
