 |
Thermionic Emission
Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature (releasing of energy supplied by heat). This occurs because the thermal energy given to the charge carrier overcomes the work function of the material. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions. After emission, a charge that is equal in magnitude and opposite in sign to the total charge emitted is initially left behind in the emitting region. But if the emitter is connected to a battery, the charge left behind is neutralized by charge supplied by the battery as the emitted charge carriers move away from the emitter, and finally the emitter will be in the same state as it was before emission. The classical example of thermionic emission is that of electrons from a hot cathode into a vacuum (also known as thermal electron emission or the Edison effect) in a vacuum tube. The hot cathode can be a metal filament, a coate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
McGraw-Hill
McGraw Hill is an American educational publishing company and one of the "big three" educational publishers that publishes educational content, software, and services for pre-K through postgraduate education. The company also publishes reference and trade publications for the medical, business, and engineering professions. McGraw Hill operates in 28 countries, has about 4,000 employees globally, and offers products and services to about 140 countries in about 60 languages. Formerly a division of The McGraw Hill Companies (later renamed McGraw Hill Financial, now S&P Global), McGraw Hill Education was divested and acquired by Apollo Global Management in March 2013 for $2.4 billion in cash. McGraw Hill was sold in 2021 to Platinum Equity for $4.5 billion. Corporate History McGraw Hill was founded in 1888 when James H. McGraw, co-founder of the company, purchased the ''American Journal of Railway Appliances''. He continued to add further publications, eventually establishin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
|
William Preece
Sir William Henry Preece (15 February 1834 – 6 November 1913) was a Welsh electrical engineer and inventor. Preece relied on experiments and physical reasoning in his life's work. Upon his retirement from the Post Office in 1899, Preece was made a Knight Commander of the Order of the Bath (KCB) in the 1899 Birthday Honours. Biography Preece was born in Caernarfon (Gwynedd), Wales. He was educated at King's College School and King's College London. Preece studied at the Royal Institution in London (Great Britain) under Michael Faraday. He later was the consulting engineer for the Post Office (1870s). He became Engineer-in-Chief of the British General Post Office in 1892. He developed several improvements in railroad signalling system that increased railway safety. Preece and Oliver Lodge maintained a correspondence during this period. Upon Lodge's proposal of "loading coils" applied to submerged cables, Preece did not realise that "Earthing" would extend the distance and effi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
|
International Electrical Exposition
International is an adjective (also used as a noun) meaning "between nations". International may also refer to: Music Albums * ''International'' (Kevin Michael album), 2011 * ''International'' (New Order album), 2002 * ''International'' (The Three Degrees album), 1975 *''International'', 2018 album by L'Algérino Songs * The Internationale, the left-wing anthem * "International" (Chase & Status song), 2014 * "International", by Adventures in Stereo from ''Monomania'', 2000 * "International", by Brass Construction from ''Renegades'', 1984 * "International", by Thomas Leer from ''The Scale of Ten'', 1985 * "International", by Kevin Michael from ''International'' (Kevin Michael album), 2011 * "International", by McGuinness Flint from ''McGuinness Flint'', 1970 * "International", by Orchestral Manoeuvres in the Dark from '' Dazzle Ships'', 1983 * "International (Serious)", by Estelle from '' All of Me'', 2012 Politics * Political international, any transnational organizati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
 |
Galvanometer
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely. A galvanometer works by deflecting a pointer in response to an electric current flowing through a coil in a constant magnetic field. Galvanometers can be thought of as a kind of actuator. Galvanometers came from the observation, first noted by Hans Christian Ørsted in 1820, that a magnetic compass's needle deflects when near a wire having electric current. They were the first instruments used to detect and measure small amounts of current. André-Marie Ampère, who gave mathematical expression to Ørsted's discovery, named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk. Galvanometers have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
 |
Incandescent Lamp
An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidation. Current is supplied to the filament by terminals or wires embedded in the glass. A bulb socket provides mechanical support and electrical connections. Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. As a result, the incandescent bulb became widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting. Incandescent bulbs are much less efficient than other types of electric lighting, converting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
 |
Thomas Edison
Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, which include the phonograph, the motion picture camera, and early versions of the electric light bulb, have had a widespread impact on the modern industrialized world. He was one of the first inventors to apply the principles of organized science and teamwork to the process of invention, working with many researchers and employees. He established the first industrial research laboratory. Edison was raised in the American Midwest. Early in his career he worked as a telegraph operator, which inspired some of his earliest inventions. In 1876, he established his first laboratory facility in Menlo Park, New Jersey, where many of his early inventions were developed. He later established a botanical laboratory in Fort Myers, Flor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Hans Friedrich Geitel") |
Hans Friedrich Geitel
Hans Friedrich Karl Geitel (16 July 1855 in Braunschweig – 15 August 1923 in Wolfenbüttel) was a German physicist. He is credited with coining the phrase "atomic energy." Biography Through the relocation of his family, his father was a forester, Hans Geitel came to Blankenburg in 1861 and grew up in close proximity to Julius Elster. He attended school and high school together with Elster. A lifelong friendship developed between the two of them, their interest in science became a shared field of activity. During their studies both spent two years in Heidelberg and Berlin. In 1879 Geitel got his teaching degree in Braunschweig and accepted a position as teacher at the then called Herzogliche Große Schule (translation: Ducal Great School) in Wolfenbüttel. In 1881 Geitel succeeded in getting Julius Elster to the school as well. There they intensified their joint researches. Karl Bergwitz (1875–1958), who continued their research, was one of their students there. In 1892 Geite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
Julius Elster
Julius Johann Phillipp Ludwig Elster (24 December 1854 in Blankenburg – 6 April 1920) was a teacher and physicist. Biography Elster and Hans Friedrich Geitel, the son of a Forstmeister who had moved to Blankenburg with his family in 1861, grew up in the same neighborhood and attended school and high school together. The personal friendship was deepened by the shared interest in the natural sciences during their years at university in Heidelberg and Berlin. After they received their teaching certification in Brunswick, they went their separate ways for a short time. In 1881 they were working together at the ''Herzogliche Große Schule'' (translation: Ducal Great School) in Wolfenbüttel and used their leisure for experimental research. There Karl Bergwitz (1875–1958) was among their students. Elster was awarded an honorary doctorate (1915) along with Geitel at the Braunschweig University of Technology. In 1919, he was diagnosed with diabetes mellitus. In April 1920, the Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
|
Eugen Goldstein
Eugen Goldstein (; 5 September 1850 – 25 December 1930) was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays or canal rays, later identified as positive ions in the gas phase including the hydrogen ion. He was the great uncle of the violinists Mikhail Goldstein and Boris Goldstein. Life Goldstein was born in 1850 at Gleiwitz Upper Silesia, now known as Gliwice, Poland, to a Jewish family. He studied at Breslau and later, under Helmholtz, in Berlin. Goldstein worked at the Berlin Observatory from 1878 to 1890 but spent most of his career at the Potsdam Observatory, where he became head of the astrophysical section in 1927. He died in 1930 and was buried in the Weißensee Cemetery in Berlin. Work In the mid-nineteenth century, Julius Plücker investigated the light emitted in discharge tubes (Crookes tubes) and the influence of magnetic fields on the glow. Later, in 1869, Johann Wilhelm Hittorf studied discharge tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
|
Johann Wilhelm Hittorf
Johann Wilhelm Hittorf (27 March 1824 – 28 November 1914) was a German physicist who was born in Bonn and died in Münster, Germany. Hittorf was the first to compute the electricity-carrying capacity of charged atoms and molecules (ions), an important factor in understanding electrochemical reactions. He formulated ion transport numbers and the first method for their measurements. He observed tubes with energy rays extending from a negative electrode. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "cathode rays" by Eugen Goldstein. Hittorf's early investigations were on the allotropes of phosphorus and selenium. Between 1853 and 1859 his most important work was on ion movement caused by electric current. In 1853 Hittorf pointed out that some ions traveled more rapidly than others. This observation led to the concept of transport number, the fraction of the electric current carried by each ionic species. He measured ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |