Electromagnetic Spectrum

The electromagnetic spectrum involves a continuous range of electromagnetic radiations of different frequencies and wavelengths. With growing frequency of radiation, the waves are shorter and their energy bigger. Radio waves with wavelength from hundreds of meters to less than one meter are used to facilitate radio communication. They are used for radio and television broadcasting, mobile phone and wireless networking, in GPS, radars, remote controls, etc. Microwaves, with a shorter wavelength, are used e. g. in Wifi networks or in microwave ovens for heating the food. Infrared radiation is discernible to humans as thermal radiation or heat. The small central part of the electromagnetic spectrum is occupied by the visible light. Electromagnetic waves of this frequency are the only ones that can be perceived by human eyes. The visible light also presents a spectrum of colours which goes from red to violet. Even shorter wavelength have ultraviolet waves, already invisible for the human eye, which together with infrared waves come from the Sun and are a common cause of sunburn. Very short electromagnetic waves with high frequency are X-rays, used for medical and industrial radiography, and gamma rays, generated by nuclear reactions, radioactive decay, etc.