Wavefront

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The wavefront is at wave propagation in a medium , a surface on which all the points the same term in a transmitter , z. B. a sound source .

Wavefronts (in black) of a straight-line (in red) propagating transverse wave
circular wave fronts (in black) of a radially (in red) propagating transverse wave

For periodic waves, all points on the wave front have the same phase . The wave front moves with the front speed of the waves in the direction of the surface normal .

The shape of the wave front depends on the one hand on the type of transmitter, i.e. H. its shape, dimensions and directional characteristics. On the other hand, the wave front depends on the type of transmission medium (e.g. air) and the prevailing conditions (e.g. in the case of sound propagation from temperatures, air movements, boundary surfaces, etc.).

In the simplest case, when a zero-order spherical emitter is operated in an isotropic and homogeneous transmission medium, a spherical wave with spherical wave fronts is created.

In the case of a plane wave , the wave fronts are planes perpendicular to the direction of propagation, in the case of periodic excitation at a distance of the wavelength . A spherical wave becomes similar to a plane wave in a small solid angle range (or at a great distance from the source).

According to Huygens principle , every point of a wave front can be considered as the starting point of a spherical elementary wave. The resulting wave front then arises from the superposition of these elementary waves. In this way, the refraction and diffraction of wave fronts can be calculated (see wave optics ).

literature

  • Joachim Loos: Construction of surfaces with specified curvature properties and applications in ophthalmic optics . Herbert Utz Verlag Wissenschaft, Munich 1998, ISBN 3-89675-275-8 .
  • Ulrich Hahn: Physics for Engineers . Volume 1: Mechanics - Thermodynamics - Vibrations and Waves. 2nd Edition. De Gruyter Verlag, Berlin 2015, ISBN 978-3-11-035056-2 -.

See also

Web links