Electromagnetic Radiation

The electromagnetic spectrum has electromagnetic waves ranging from 103m-1012m.

  • It includes radio waves, microwaves, infrared, visible region, UV,X-rays and gamma rays.
  • Electromagnetic wave with maximum wavelength – Radio waves.
  • Waves used for communication through satellites – Micro wave.


  • X-rays are electro magnetic waves with shorter wavelength.
  • X-rays were discovered by Rongen.
  • It is used to study the internal atomic structure of crystals.
  • Hard X-rays are of higher frequencies with more penetrating power than soft X-rays.
  •  Hard X-rays are used in radiations and the treatment of cancer as it penetrates into the body tissues.
  • Soft X-rays are used in the photography of internal parts such as chest and bone.
  • The rays which appears to be originated from outside of the earth is called Cosmic rays.
  • Cosmic rays were discovered by Victor Hess.

Infrared rays

  • Was discovered by William Herschel.
  • Used in T.V. remotes.
  • Used in distant photography.
  • The heat of the sunlight is due to – Infrared rays.

Ultraviolet rays

  • Used for detecting the adulterations in ghee and is also used for identifying the counterfeit currency.
  • They causes sun burn.
  • UV ray is used to disinfect equipments used for operations.
  • It is used to fill inside the tube light.