free-space propagation
81Telecommunication — A parabolic satellite communication antenna at the biggest facility for satellite communication in Raisting, Bavaria, Germany …
82Laser diode — Top: a packaged laser diode shown with a penny for scale. Bottom: the laser diode chip is removed from the above package and placed on the eye of a needle for scale …
83List of electronics topics — Alphabetization has been neglected in some parts of this article (the b section in particular). You can help by editing it. This is a list of communications, computers, electronic circuits, fiberoptics, microelectronics, medical electronics,… …
84Wi-Fi — For the radio station, see WIFI (AM). Wi Fi logo Wi Fi (  / …
85Equivalence principle — General relativity|cTopic=Fundamental conceptsThe equivalence principle is one of the fundamental background concepts of the General Theory of Relativity. For the overall context, see General relativity.In the physics of relativity, the… …
86Nikola Tesla — Tesla, aged 37, 1893, photo by Sar …
87Time in physics — In physics, the treatment of time is a central issue. It has been treated as a question of geometry. One can measure time and treat it as a geometrical dimension, such as length, and perform mathematical operations on it. It is a scalar quantity… …
88Gaussian beam — In optics, a Gaussian beam is a beam of electromagnetic radiation whose transverse electric field and intensity (irradiance) distributions are well approximated by Gaussian functions. Many lasers emit beams that approximate a Gaussian profile, in …
89Dispersion relation — The refraction of a light in a prism is due to dispersion. In physics and electrical engineering, dispersion most often refers to frequency dependent effects in wave propagation. Note, however, that there are several other uses of the word… …
90Aether theories — See also the disambiguation page for Aether. Alchemy, natural philosophy, and early modern physics proposed the existence of a medium of the æther (also spelled ether , from the Greek word (Polytonic|αἰθήρ) aether , meaning upper air or pure,… …
