|
Light Rail In Missouri
Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz. The visible band sits adjacent to the infrared (with longer wavelengths and lower frequencies) and the ultraviolet (with shorter wavelengths and higher frequencies), called collectively '' optical radiation''. In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum, and polarization. Its speed in vacuum, , is one of the fundamental constants of nature. All electromagnetic radiation exhibits some properties of both particles and waves. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prism Flat Rainbow (cropped)
PRISM is a code name for a program under which the United States National Security Agency (NSA) collects internet communications from various U.S. internet companies. The program is also known by the SIGINT Activity Designator, SIGAD . PRISM collects stored internet communications based on demands made to internet companies such as Google LLC and Apple Inc., Apple under Section 702 of the FISA Amendments Act of 2008 to turn over any data that match court-approved search terms. Among other things, the NSA can use these PRISM requests to target communications that were encrypted when they traveled across the internet backbone, to focus on stored data that telecommunication filtering systems discarded earlier, and to get data that is easier to handle. PRISM began in 2007 in the wake of the passage of the Protect America Act under the Presidency of George W. Bush, Bush Administration. The program is operated under the supervision of the United States Foreign Intelligence Surveill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
