Units of Resistor

The SI unit of electrical resistance is the ohm (Ω). A component has a resistance of 1 Ω if a voltage of 1 volt across the component results in a current of 1 ampere, or amp, which is equivalent to a flow of one coulomb of electrical charge (approximately 6.241506 × 1018 electrons) per second. The multiples kiloohm (1 kΩ = 1000 Ω) and megaohm (1 MΩ = 106 Ω) are also commonly used.

In an ideal resistor, the resistance remains constant regardless of the applied voltage or current through the device or the rate of change of the current. Whereas real resistors cannot attain this goal, they are designed to present little variation in electrical resistance when subjected to these changes, or to changing temperature and other environmental factors.

Television History

Television was not invented by a single person, but by the contributions of several individuals. The origins of what would become today's television system can be traced back to the discovery of the photoconductivity of the element selenium by Willoughby Smith in 1873 followed by the work on the telectroscope and the invention of the scanning disk by Paul Nipkow in 1884. All practical television systems use the fundamental idea of scanning an image to produce a time series signal representation. That representation is then transmitted to a device to reverse the scanning process. The final device, the television (or TV set), relies on the human eye to integrate the result into a coherent image.

Television

Television is a telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term has come to refer to all the aspects of television from the television set to the programming and transmission. The word is derived from mixed Latin and Greek roots, meaning "far sight": Greek "tele", far, and Latin visio-n, sight (from video, vis- to see).