We have to arrange electromagnetic waves in order of increasing wavelength
Wavelength of γ rays=<10−3nm
Wavelength of micro waves = 0.1mm to 1mm
Wavelength of X rays=1nm to 10−3nm
Wavelength of Radio waves=>0.1m
Smaller wavelength wave=γ rays
Larger wavelength wave=Radio waves
γ rays < X rays < Microwave rays < Radio waves
⇒ Infrared waves are produced by hot bodies and molecules. This band lies adjacent to low frequency or long wavelength end of visible spectrum.Infrared waves are sometimes referred to as heat waves. This is because water molecules present in most of the materials readily absorb infered waves. After absorbtion, their thermalmotion increase, that is they heat up and heat their surroundings.
⇒ Infrared radiation maintains the earth's warmth through greenhouse effect. Incoming visible light (which passes relatively easily through atmosphere) is absorb by earth's surface and reradiated as infrared radiation. This radiation is trapped by green house gases such as carbon dioxide and water vapour.
⇒ Physical therapies are used to cure injuries, increase strength. Infrared radiation are penetrated into body to gencrak theocratic benefits via amplyfeed blood flow and tissue oxygenation.The quick increase of blood flow and tissue oxygenation can help encouraging the generation of energy needed for heating.