Explain briefly (i) Infra red rays, (ii) Ultra violet rays, (iii) Gamma rays.

Explanation

(i) Infra red rays : It is produced from hot bodies and also when the molecules undergo rotational and vibrational transitions. The wavelength range is ` 8 xx 10 ^(-7) m ` to ` 5xx 10 ^(-3) ` m and frequency range are ` 4 xx 10 ^(14) Hz ` to ` 6 xx 10 ^(10 ) ` Hz. It provides electrical energy to satellites by means of solar cells. It is used to produce dehydrated fruits, in green houses to keep the plants warm, heat therapy for muscular pain or sprain, TV remote as a signal carrier, to look through haze fog or mist and used in night vision or infrared photography.
(ii) Ultraviolet rays : It is produced by Sun, arc andd ionized gases. The wavelength range is ` 6 xx 10 ^(-10) m ` to ` 4 xx 10^(-7) m ` and frequency range are ` 5 xx 10 ^(17) Hz ` to ` 7 xx 10 ^(14) Hz`. It has less penetrating power. It can be absorbed by atmospheric ozone and harmful to human body. It is used to destroy bacteria, sterilizing the surgical instruments, burglar alarm, detect the invisible writing, finger prints and also in the study of molecular structure.
(iii) Gamma rays : It is produced by transitions of atomic nuclei and decay of certain elecmentary particles. They produce chemical reactions on photographic plates, fluorescene, ionisation, diffraction. The wavelength range is ` 1 xx 10 ^(-14) m ` to ` 1 xx 10 ^(-10) m` and frequency range are ` 3 xx 10 ^(22) Hz ` to ` 3 xx 10 ^(18) ` Hz. Gamma rays have high penetrating power that X - rays and ultraviolet radiations , it has no charge but harmful to human body. Gamma rays provide information about the structure of atomic nuclei. it is used in radio therapy for the treatment of cancer and tumour, in food industry to kill pathogenic microorganism.