Electromagnetic spectrum

The Electromagnetic Spectrum is the name given to the range of electromagnetic waves covering all frequencies and wavelengths. It includes radio and television transmission, Microwaves, Infrared, visible light, Ultraviolet, X-rays, and Gamma rays.

Electromagnetic radiation

All electromagnetic radiation can be described in terms of its Energy (E), frequency (f), wavenumber (v'), or wavelength ($\lambda$). These properties are all related by the following equations:

$\lambda ={\frac {c}{f}}\,\!$ ,

$E=hf\,\!$ ,

where c = 299,792,458 m/s (the speed of light) and h = 6.626 x 10^-34 Js (Planck's constant)

As well as the wavelike properties of EM radiation several effects particularly of the emission and absorption of light behave like particles. That is, the energy carried by light waves is packaged in discrete bundles called photons or quanta. The particle character of light is described in quantum electrodynamics, a theory which began with Dirac's work of 1927.

Further reading

• Young and Freedman. University Physics. Addison-Wesley Publishing Company. ISBN 0-201-31132-1
• NASA introduction to electromagnetic spectrum