Einfallendes

Einfallendes is the attributive form of the German present participle einfallend, derived from the verb einfallen. It functions as an adjective and is used to describe something that falls onto or strikes a surface, or more generally something incoming or incident. The term is particularly common in scientific and technical contexts, especially in optics and physics, where it appears in phrases such as einfallendes Licht (incident light) or einfallende Strahlen (incident rays). It is used to distinguish incoming components from reflected or transmitted ones, for example reflected light (reflektiertes Licht) or transmitted light (transmittiertes Licht).

In usage, einfallende typically agrees with the noun it modifies in gender, number, and case. Examples include das einfallende Licht (neuter singular, nominative/accusative) and einfallende Strahlen (plural). The form can also describe non-physical phenomena metaphorically, as in einfallende Gedanken (ideas that occur to someone).

A related term is der Einfallswinkel, the angle of incidence, which describes the angle at which the incoming wave or ray strikes a surface. Einfallendes contrasts with eingefallen, the past participle meaning collapsed, or with ideas that have already occurred to someone.

Etymologically, einfallend comes from the verb einfallen, literally “to fall onto/into,” extended sense to mean something that falls in or comes to mind, and by extension to describe incoming or incident phenomena.