Portal:Electronics
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Portal:Electronics

## The Electronics Portal

Surface-mount electronic components

Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active devices to control electron flow by amplification and rectification, which distinguishes it from classical electrical engineering which uses passive effects such as resistance, capacitance and inductance to control current flow.

Electronics has had a major effect on the development of modern society. The identification of the electron in 1897, along with the subsequent invention of the vacuum tube which could amplify and rectify small electrical signals, inaugurated the field of electronics and the electron age. This distinction started around 1906 with the invention by Lee De Forest of the triode, which made electrical amplification of weak radio signals and audio signals possible with a non-mechanical device. Until 1950, this field was called "radio technology" because its principal application was the design and theory of radio transmitters, receivers, and vacuum tubes.

The term "solid-state electronics" emerged after the first working transistor was invented by William Shockley, Walter Houser Brattain and John Bardeen at Bell Labs in 1947. The MOSFET (MOS transistor) was later invented by Mohamed Atalla and Dawon Kahng at Bell Labs in 1959. The MOSFET was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses, revolutionizing the electronics industry, and playing a central role in the microelectronics revolution and Digital Revolution. The MOSFET has since become the basic element in most modern electronic equipment, and is the most widely used electronic device in the world.

Electronics is widely used in information processing, telecommunication, and signal processing. The ability of electronic devices to act as switches makes digital information-processing possible. Interconnection technologies such as circuit boards, electronics packaging technology, and other varied forms of communication infrastructure complete circuit functionality and transform the mixed electronic components into a regular working system, called an electronic system; examples are computers or control systems. An electronic system may be a component of another engineered system or a standalone device. most electronic devices use semiconductor components to perform electron control. Commonly, electronic devices contain circuitry consisting of active semiconductors supplemented with passive elements; such a circuit is described as an electronic circuit. Electronics deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes, integrated circuits, optoelectronics, and sensors, associated passive electrical components, and interconnection technologies. The nonlinear behaviour of active components and their ability to control electron flows makes amplification of weak signals possible.

The study of semiconductor devices and related technology is considered a branch of solid-state physics, whereas the design and construction of electronic circuits to solve practical problems come under electronics engineering. This article focuses on engineering aspects of electronics. (Full article...)

## Selected biography

Max Karl Ernst Ludwig Planck (April 23, 1858 – October 4, 1947) was a German physicist. He is considered to be the founder of quantum theory, and therefore one of the most important physicists of the twentieth century. In 1894 Planck turned his attention to the problem of black-body radiation. By interpolating between Wien's law[disambiguation needed] and the Rayleigh-Jeans law, Planck found the famous Planck black-body radiation law, which described the experimentally observed black-body spectrum very well. The discovery of Planck's constant enabled him to define a new universal set of physical units (such as the Planck length and the Planck mass), all based on fundamental physical constants.

## Selected design

Credit: commons:User:Jjbeard
Circuit diagram of a simple Crowbar circuit, with an 8V nominal output (7.6V with SD1).

## Selected article

In physics, Coulomb's law is an inverse-square law indicating the magnitude and direction of electrostatic force that one stationary, electrically charged object of small dimensions exerts on another. It is named after Charles-Augustin de Coulomb who used a torsion balance to establish it.

The magnitude of the electrostatic force between two point charges is directly proportional to the magnitudes of each charge and inversely proportional to the square of the distance between the charges.

For calculating the direction and magnitude of the force simultaneously, one will wish to consult the full vector version of the Law

${\displaystyle {\vec {F}}={\frac {1}{4\pi \epsilon _{0}}}{\frac {q_{1}q_{2}}{|{\vec {r}}|^{3}}}{\vec {r}}={\frac {1}{4\pi \epsilon _{0}}}{\frac {q_{1}q_{2}}{|{\vec {r}}|^{2}}}{\hat {r}}}$
where ${\displaystyle {\vec {F}}}$ is the electrostatic force vector, ${\displaystyle q_{1}}$ is the charge on which the force acts, ${\displaystyle q_{2}}$ is the acting charge, ${\displaystyle {\vec {r}}={\vec {r_{1}}}-{\vec {r_{2}}}}$ is the distance vector between the two charges, ${\displaystyle {\vec {r_{1}}}\ }$ is position vector of ${\displaystyle q_{1}}$, ${\displaystyle {\vec {r_{2}}}\ }$ is position vector of ${\displaystyle q_{2}}$, ${\displaystyle {\hat {r}}}$ is a unit vector pointing in the direction of ${\displaystyle {\vec {r}}}$, and ${\displaystyle \epsilon _{0}}$ is a constant called the permittivity of free space.

This vector equation indicates that opposite charges attract, and like charges repel. When ${\displaystyle q_{1}q_{2}\ }$ is negative, the force is attractive. When positive, the force is repulsive.

## Consumer showcase

Wi-Fi is a brand originally licensed by the Wi-Fi Alliance to describe the underlying technology of wireless local area networks (WLAN) based on the IEEE 802.11 specifications. It was developed to be used for mobile computing devices, such as laptops, in LANs, but is now increasingly used for more services, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics such as televisions and DVD players, or digital cameras. More standards are in development that will allow Wi-Fi to be used by cars in highways in support of an Intelligent Transportation System to increase safety, gather statistics, and enable mobile commerce (see IEEE 802.11p).

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