Cars became widely available in the early 20th century. The year 1886 is regarded as the birth year of the car when German inventor Carl Benz patented his Benz Patent-Motorwagen. Most definitions of cars say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people rather than goods.Ĭars came into global use during the 20th century, and developed economies depend on them. The brand is now managed by GIP Development SARL of Luxembourg and is used on various product groups worldwide.Ī car (or automobile) is a wheeled motor vehicle used for transportation. It filed for bankruptcy in late 2015 with liquidation proceedings completed in early 2016. It was owned by Robert Bosch GmbH from 1933 until 1 March 2009, when it was sold to Aurelius AG of Germany. As of September 2019, the darkest material is made by MIT engineers from vertically aligned carbon nanotubes.īlaupunkt GmbH ( listen) was a German manufacturer of mostly car audio equipment. Similarly, black text on a white screen is the most common format used on computer screens. According to surveys in Europe and North America, it is the color most commonly associated with mourning, the end, secrets, magic, force, violence, evil and elegance.īlack ink is the most common color used for printing books, newspapers and documents, as it provides the highest contrast with white paper and thus is the easiest color to read. It became the color worn by English romantic poets, businessmen and statesmen in the 19th century, and a high fashion color in the 20th century. In the 14th century, it was worn by royalty, clergy, judges and government officials in much of Europe. In the Roman Empire, it became the color of mourning, and over the centuries it was frequently associated with death, evil, witches, and magic. It was used in ancient Egypt and Greece as the color of the underworld. Since the Middle Ages, black has been the symbolic color of solemnity and authority, and for this reason is still commonly worn by judges and magistrates.īlack was one of the first colors used by artists in neolithic cave paintings. Black and white have often been used to describe opposites such as good and evil, the Dark Ages versus Age of Enlightenment, and night versus day. It is often used symbolically or figuratively to represent darkness. It is an achromatic color, without hue, like white and gray. Today most amplifiers use transistors.īlack is a color which results from the absence or complete absorption of visible light. The first practical electrical device which could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Amplifiers can also be categorized by their physical placement in the signal chain a preamplifier may precede other signal processing stages, for example. For example, audio amplifiers amplify signals in the audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz, and servo amplifiers and instrumentation amplifiers may work with very low frequencies down to direct current. One is by the frequency of the electronic signal being amplified. Amplifiers can be categorized in different ways. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment.
An amplifier is a circuit that has a power gain greater than one.Īn amplifier can either be a separate piece of equipment or an electrical circuit contained within another device. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. It is the smallest composite number, and is considered unlucky in many East Asian cultures.Īn amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current).
It is the natural number following 3 and preceding 5. 4 ( four) is a number, numeral and digit.
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