Infra Red Spectrum Homework Help, Assignment Help, Online Tutor, Tutoring

Submit Assignment

* *

Payment Online Assignment Help

Thermodynamics

Homework Help

sfsf

Infra Red Spectrum

Extending on either side of the visible spectrum there are invisible radiations which do not cause the sensation of sight. The radiations beyond the red end of the visible spectrum are called infra-red radiations and their wavelength extend upto 400000 Å. Sun is a powerful source of infra-red radiations. Beyond the violet end of the visible spectrum, the radiations extending up to a wavelength of 100 Å are called ultra-violet radiations.

The heating effect of the infra-red radiations is used in measuring the wavelength of the radiation. An infra-red ray spectrometer is shown in fig. Light from a strong source of light, such as an electric arc, is rendered parallel by reflection from a concave stainless steel mirror M₁. This parallel beam is refracted through the rock salt prism P and the emergent dispersed beam after reflection from the mirrors M₁ and M₂ is incident on a thermopile or a bolometer. M₂ is a plane mirror and M₂ is a concave mirror. Wien’s law of radiation is given by

λmT = 0.2885

where T is the absolute temperature and λm is the wavelength of the radiation. The thermopile readings help in the calculation of temperature and from the temperature, λ can be calculated.

As infra-red radiations are not absorbed by air ir thick fog, infra-red ray photographs can be taken over long distances of fog and mist where visible light cannot penetrate. For this, specially designed photographic plates are used with suitable filters. A solution of iodine in alcohol is a suitable filter, because this transmits the infra-red radiations and absorbs the visible light. In the World War II, infra-red photography played a very useful part in detecting objects in the dark through mist, for and clouds. Infra-red radiations have a wide application in the field of medicine, industry etc. Infra-red radiations have a wide application in the field of medicine, industry etc. Infra-red radiations can penetrate deep into the human body and by their property of heating can dilate the blood vessels at the portion exposed to the radiations. This enables the increased flow of blood.