→IR (Infrared) waves are produced by hot bodies and molecules.
→I.R. waves are sometimes referred to as heat waves. This is because water molecules present in most materials readily absorb infrared waves. (many other molecules, for example, CO2, NH3 also absorb infrared waves) After absorption, their thermal motion increases, that is, they heat up and heat the surroundings.
→Range of wavelength from 7 mm to 700 nm.
→Infrared lamps are used in physical therapy.
→Infrared radiation also plays an important role in maintaining the earth's warmth or average temperature through the greenhouse effect.
→I.R. detectors are used in Earth satellites, both for military purposes and to observe growth of crops.
→Electronic devices (semiconductor LEDs) also emit infrared and are widely used in remote switches of household electronic systems such as, TV sets, Video recorders and hi-fi systems.