What is infrared radiation?

please clear my concept from a to z, but with concise explanation.

1 Answer
Jun 28, 2016

Radiation with wavelength longer than red light (700 nm). (Range = 700nm to 1mm)
Alternatively, it is radiation with frequency lower than red light.


All objects beyond absolute zero (0 Kelvin), which indicates all objects, radiate energy in energy packets called photons. How much energy a photon may contain is quantized, that is to say, there are definite energy levels between two of which, no photon may be radiated. The energy content of the object is expressed as temperature. That is, if an object has molecules vibrating rapidly (high energy), it has high temperature.

Photons are electromagnetic waves and their color (fundamentally frequency) is a function of energy content, given by the equation:

#E = h*nu#,
E = Energy Content
h = Planck's constant
#nu# = frequency of radiation.

Objects with high temperature radiate with high frequency (Ultraviolet rays, X-rays, Gamma Rays, Cosmic Rays) and objects with low temperature radiate with low frequency (Radio waves, Microwaves, infrared rays). Visible light falls between Infrared and Ultraviolet rays in terms of frequency.

Infrared rays are expressed as heat. Thermal imaging takes place through infrared scanning.