### plane wave

**(plane parallel wave)**
(simplified wave concept useful for modeling)

A **plane wave** (or **plane parallel wave**)
is a theoretical wave such that the motions/changes occurring
are the same across an entire mathematical plane, and the
wave is traveling perpendicular to the plane. This is
mathematically simpler than waves diverging from something,
e.g., as expanding spheres,
but a sub-region consisting of a small fraction of such an
expanding sphere approximates a plane, and as such a wave
progresses, using a *plane wave* as an approximation of the wave becomes
more and more useful. Thus, a wave far from its source is often modeled
as a plane wave to generalize the model and simplify the math. This
is analogous to the "plane-parallel atmosphere" simplified model
of atmospheres

Such a wave (if longitudinal) also approximates a wave
within a cylindrical musical wind instrument such as a flute or
organ pipe, one complicating factor being the effect of friction
between the medium (air) and the surrounding inner pipe surface.

(*waves,mathematics,models*)
**Further reading:**

http://en.wikipedia.org/wiki/Plane_wave

**Referenced by pages:**

coherent light

Hellings and Downs curve

wavefront error (WFE)

Index