Radiation

The term radiation refers to the propagation of particles or waves. In the first case of particle radiation or corpuscular saith in the second wave of radiation.

The distinction between particles and waves is historic and has as approximate, descriptive statement still important. However, according to current knowledge, has any radiation both particle and wave properties.

Use of the word

Rays, the plural of, beam ', is sometimes used synonymously with the term radiation, even in compositions such as " alpha rays " or " x-rays ". A singular such as "X-Ray ", however, almost always referred to a beam, which is directed and transports energy and momentum. When the beam of particles with mass, charge or other properties is, these are also transported. " Ray of light ", however, can both the idealized linear beam (see Geometrical Optics ) or a beam mean. The ambiguity of the German word beam is also reflected in the fact that in other languages ​​, respectively, there are several different expressions for it. In English, referred ray, for example, an idealized beam, beam a beam jet a jet of matter.

The propagation of sound waves or other mechanical follows laws similar propagation of electromagnetic radiation. They are still hardly known as radiation.

Basics

The radiation hits an obstacle, it is either absorbed ( taken up and converted ), unaffected transmitted ( allowed to pass ), scattered or reflected ( echoed ) (see also remission).

The historical debate over whether light rays consist of particles or waves, was answered in quantum physics so that a light beam of photons is whose abode is described in quantum mechanics by a probability wave. This probability waves can interfere with each other (see double -slit experiment ). Louis de Broglie showed in his theory of matter waves that each particle has a wavelength can be assigned. This explains why, for example, an electron also shows interference phenomena. ( See also wave -particle duality. )

Characterization

A distinction radiation to its components, according to their source or by their impact.

Electromagnetic waves consist of photons. Electromagnetic waves having a short wavelength, so a high photon energy are often referred to in the parlance as electromagnetic radiation, such as X-rays, bremsstrahlung, UV radiation, thermal radiation or infrared radiation. In the long wavelength region we speak rather of waves, such as radio waves.

The terms particle and particle radiation are sometimes used as generic terms for radiation whose components have a nonzero mass.

Particle are categorized according to the variety of the particles of which it consists, for example, alpha radiation ( α - particles ), beta rays ( electrons or positrons) or neutron radiation.

Radiation from space are categorized according to their source in solar radiation, cosmic radiation, background radiation and Hawking radiation. Radiation emitted by radioactive materials, is often referred to as the nuclear radiation, although the radiation is not radioactive, but the emitting material. The radiation due to the natural radioactivity of the earth is called terrestrial radiation.

Is the energy of the ray particles so high that it can be removed from atoms or molecules of electron radiation is called the ionizing radiation. Electromagnetic waves in this energy often give the first strike from a lot of their energy. For the energy and material dependence, see mass attenuation coefficient. Charged particles with high energy hand it in when passing through matter in many small portions. For the energy and material dependence see stopping power.