These waves were discovered by William Herschel (1737-1822) in 1800.

All hot bodies are sources of infrared rays.

About 60% of the solar radiations are infrared in nature. Thermocouples, thermopile and bolometers are used to detect infrared rays.

Properties

1) When infrared rays are incident on any object, the object gets heated.

2) These rays are strongly absorbed by glass.

3) They can penetrate through thick columns of fog, mist and cloud cover.

Uses

1) Used in remote sensing.

2) Used in diagnosis of superficial tumours and varicose veins.

3) Used to cure infantile paralysis and to treat sprains, dislocations and fractures.

4) They are used in Solar water heaters and cookers.

5) Special infrared photographs of the body called thermograms, can reveal diseased organs because these parts radiate less heat than the healthy organs.

6) Infrared binoculars and thermal imaging cameras are used in military applications for night vision.

7) Used to keep green house warm.

8) Used in remote controls of TV, VCR, etc