Write any three uses of infrared radiations.

Hint
Infrared radiations are the part of the electromagnetic spectrum that have a frequency range from $3 \times {10^{11}}$ Hz to about $4 \times {10^{14}}$ Hz. Infrared radiations are also referred to as heat radiations.

Complete step by step answer
Infrared radiations lie near to the low frequency of the long-wavelength end of the visible light spectrum; these are made by hot bodies and vibrations of molecules and atoms. It can be observed that water molecules present in most materials absorb infrared radiations that cause heating effects in their surroundings. This is the reason infrared radiations are termed as heat radiations. A daily life example of infrared radiation is observed in the heat we experience from sunlight. Uses of infrared radiations are as follows:
(i) Infrared waves are used in infrared lamps in physical therapy for the treatment of muscular strains. These are used in infrared detectors in satellites to observe the growth of crops and in defense forces.
(ii) Infrared radiations play a substantial role in the maintenance of warmth of earth through the greenhouse effect. When the light coming from the Sun is absorbed by the surface of the earth it gets re-radiated as infrared radiations, it is trapped by greenhouse gases. This results in the maintenance of heat conditions in the surface and atmosphere of the earth.
(iii) Infrared radiations are used in night vision devices, heat lamps, and fiber optic cables.

Note
Infrared radiations lie in between the microwaves and visible light rays in the electromagnetic spectrum. The frequency range of infrared radiations must not be confused with the microwaves and visible light rays.