Elecromagnetic Spectra, EMR


The entire range over which the electromagnetic radiation exists is known as electromagnetic spectrum. This electromagnetic spectrum ranges from very short wavelengths (including gamma and x-rays) to very long wavelengths (including microwaves and broadcast radio waves). The following chart displays many of the important regions of this spectrum.

Fig. 2:  The electromagnetic spectrum

According to the fig. 2, the major characteristics of various spectrum regions are as follows:

  1. γ-rays- It lies between 0.2 to 10 nm. They are the shortest waves. They are emitted by atomic nuclei, involving energy changes of 109 to 1011 joules/gram atom.


  1. x – Rays – it lies between 10 nm TO 100 nm. It is emitted or absorbed by movement of electrons. X- Rays are used for diagnostic purpose.


  1. visible and ultraviolet region- UV radiation lies between 200 nm to 400 nm. Visible region lies between 400 nm to 800 nm.


  1. Infrared region- infrared region is further divided in three regions.
  • Near infrared region lies between 800 nm to 4000 nm.

  • Middle infrared region lies between 4000 nm to 25000 nm.

  • Far infrared region lies between 25000 nm to 100000 nm.

  1. Microwave region- This region lies between 106 nm to 107 nm. Microwaves are used in telecommunication.


     6.   Radio frequency region- radio frequency region lies between 107 nm to 109 nm.