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# Electromagnetic spectrum

(Redirected from EM spectrum)

Definition

noun

The spectrum of all types of electromagnetic radiation

Supplement

The electromagnetic spectrum includes all types of electromagnetic radiation. Electromagnetic radiation consists of electromagnetic waves, which may be characterized by frequency or wavelength of their oscillations. Based on wavelengths, the electromagnetic radiation may be: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. The amount of energy depends on the length of the wavelength. The shorter the wavelength, the higher the energy is.

Radio waves have wavelengths of 300 millimetres or longer (even up to several kilometres). Radiation of this type is used to broadcast radio and television signals, and has frequencies up to thousands of megahertz (or one gigahertz). Microwaves have wavelengths ranging from one meter to one millimeter, and with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). [[[Infrared]] is that portion of the electromagnetic spectrum with wavelengths between 770 and 1000 nm. Visible light is the electromagnetic radiation at wavelengths between 400 nanometres and 750 nanometres. It can be detected by the human eye and is responsible for the sense of sight. Ultraviolet rays are rays characterized generally by having a wavelength between 10 nm and 400 nm. X-rays are rays characterized by wavelengths ranging from 0.01 to 10 nm, and at frequencies ranging from 30 petahertz to 30 exahertz, and having energies in the range of 100 eV to 100 keV. Gamma rays are very powerful and penetrating, high-energy rays. They have the shortest wavelength (less than a nanometer) among the other forms of electromagnetic radiation. They are emitted by a decaying nucleus, usually between 0.01 and 10 mev.

Abbreviation / Acronym:

• EM spectrum