As electromagnetic spectrum or electromagnetic wave spectrum is defined as the totality of all electromagnetic waves of different energies. The spectrum is divided into different areas for better differentiation. This division is arbitrary and is geared for historical reasons the low-energy range of the wavelength. In each wavelength ranges are summarized over several orders of magnitude with similar characteristics into categories such as light, radio waves, etc.. A subdivision can also be made according to the frequency or the energy of the single photon ( see below). In a very short wavelength, corresponding to a high quantum energy, a classification according to energy is common.
Ascending order of frequency, and thus decreasing wavelength located at the beginning of the spectrum the longitudinal waves whose wavelengths are many miles. At the end are the very short wavelength and thus energy gamma rays whose wavelength ranges down to atomic dimensions.
The conversion of the wavelength is performed in a frequency f represented by the formula, that is the speed of light ( in the respective medium ) divided by the wavelength.
In some respects behave electromagnetic waves like a stream of particles called photons. This approach is necessary in order to explain some physical phenomena such as the photoelectric effect. Each photon carries an energy proportional to the frequency. The constant is the Planck constant. The energy is given in the following table in Joules ( J ), and in electron volts (eV).
Cases in which the model is appropriate, the article electromagnetic wave will be explained using examples.
Excitation of nuclear magnetic resonance and electron spin resonance, molecular rotations
Excitation of inner electrons, Auger electrons