electromagnetic trough
21History of perpetual motion machines — The history of perpetual motion machines dates back to the Middle Ages. For millennia, it was not clear whether perpetual motion devices were possible or not, but the development of modern thermodynamics has indicated that they are impossible.… …
22Mechanical wave — Ripple (surface wave) in water is a material wave. A mechanical or material wave is a wave that needs a medium to travel. The oscillating material does not move far from its initial equilibrium position, as only the energy is transferred by… …
23Kambalda type komatiitic nickel ore deposits — Kambalda type nickel ore deposits are a class of magmatic nickel copper ore deposit in which the physical processes of komatiite volcanology serve to enrich, concentrate and deposit nickel bearing sulfide within the lava flow environment of an… …
24Ionosphere — The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner …
25printing — /prin ting/, n. 1. the art, process, or business of producing books, newspapers, etc., by impression from movable types, plates, etc. 2. the act of a person or thing that prints. 3. words, symbols, etc., in printed form. 4. printed material. 5.… …
26Sustainable energy — Renewable energy …
27textile — /teks tuyl, til/, n. 1. any cloth or goods produced by weaving, knitting, or felting. 2. a material, as a fiber or yarn, used in or suitable for weaving: Glass can be used as a textile. adj. 3. woven or capable of being woven: textile fabrics. 4 …
28Quasar — This article is about the astronomical object. For other uses, see Quasar (disambiguation). Artist s rendering of ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun[1]. Credit: ESO/M.… …
29Amplitude — is the magnitude of change in the oscillating variable, with each oscillation, within an oscillating system. For instance, sound waves are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during …
30Compass — This article is about the direction finding instrument used in navigation. For other uses, see Compass (disambiguation). A simple dry magnetic pocket compass …
