PHASE (2)

Phase (?), n. 1. 1. (Phys. Chem.) A homogenous, physically distinct portion of matter in a system not homogeneous; as, the three phases, ice, water, and aqueous vapor. A phase may be either a single chemical substance or a mixture, as of gases.
2. 2. (Zoöl.) In certain birds and mammals, one of two or more color variations characteristic of the species, but independent of the ordinary seasonal and sexual differences, and often also of age. Some of the herons which appear in white and colored phases, and certain squirrels which are sometimes uniformly blackish instead of the usual coloration, furnish examples. Color phases occur also in other animals, notably in butterflies.
3. 3. (Elec.) The relation at any instant of a periodically varying electric magnitude, as electro-motive force, a current, etc., to its initial value as expressed in factorial parts of the complete cycle. It is usually expressed in angular measure, the cycle beb four right angles, or 360°. Such periodic variations are generally well represented by sine curves; and phase relations are shown by the relative positions of the crests and hollows of such curves. Magnitudes which have the same phase are said to be in phase.