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Ampere-turn
The ampere-turn (A⋅t) is the MKS (metre–kilogram–second) unit of magnetomotive force (MMF), represented by a direct current of one ampere flowing in a single-turn loop in a vacuum. " Turns" refers to the winding number of an electrical conductor composing an inductor. For example, a current of flowing through a coil of 10 turns produces an MMF of . By maintaining the same current and increasing the number of loops or turns of the coil, the strength of the magnetic field increases because each loop or turn of the coil sets up its own magnetic field. The magnetic field unites with the fields of the other loops to produce the field around the entire coil, making the total magnetic field stronger. The strength of the magnetic field is not linearly related to the ampere-turns when a magnetic material is used as a part of the system. Also, the material within the magnet carrying the magnetic flux "saturates" at some point, after which adding more ampere-turns has little ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turn (geometry)
A turn is a unit of plane angle measurement equal to radians, 360 degrees or 400 gradians. Subdivisions of a turn include half-turns, quarter-turns, centiturns, milliturns, etc. The closely related terms ''cycle'' and ''revolution'' are not equivalent to a turn. Subdivisions A turn can be divided in 100 centiturns or milliturns, with each milliturn corresponding to an angle of 0.36°, which can also be written as 21′ 36″. A protractor divided in centiturns is normally called a "percentage protractor". Binary fractions of a turn are also used. Sailors have traditionally divided a turn into 32 compass points, which implicitly have an angular separation of 1/32 turn. The ''binary degree'', also known as the '' binary radian'' (or ''brad''), is turn. The binary degree is used in computing so that an angle can be represented to the maximum possible precision in a single byte. Other measures of angle used in computing may be based on div ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MKS System Of Units
The MKS system of units is a physical system of measurement that uses the metre, kilogram, and second (MKS) as base units. It forms the base of the International System of Units (SI), though SI has since been redefined by different fundamental constants. History By the 19th century, there was a demand by scientists to define a coherent system of units. A coherent system of units is a system of units where all units are directly derived from a set of base units, without the need of any conversion factors. The United States customary units are an example of a non-coherent set of units. In 1874, the British Association for the Advancement of Science (BAAS) introduced the CGS system, a coherent system based on the centimetre, gram and second. These units were inconvenient for electromagnetic applications, since electromagnetic units derived from these did not correspond to the commonly used ''practical units'', such as the volt, ampere and ohm. After the Metre Convention of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Francis Upton
Francis Robbins Upton (1852 in Peabody, Massachusetts – March 10, 1921 in Orange, New Jersey) was an American physicist and mathematician. Upton worked alongside Thomas Edison in the development of incandescent light bulbs, electric generators, and electric power distribution. He was the first president of the Edison Pioneers. Early life Francis Upton was the son of Elijah Wood Upton and Lucy Elizabeth Winchester. Elijah was well educated and after, he did European travel. Later he was forced to take over his father's glue business due to his father's illness. Francis was 16 by this time and studying at Phillips Academy in Andover, after he received a Bachelor of Science degree in 1875 at Bowdoin College in Brunswick, ME. There he met Elizabeth F. Perry, later to become his wife. Francis Upton also attended Berlin University and Princeton University. Francis was the first ever to officially receive his doctoral degree from Princeton University. Upton was then hired by Thomas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solenoid
upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whose length is substantially greater than its diameter, which generates a controlled magnetic field. The coil can produce a uniform magnetic field in a volume of space when an electric current is passed through it. The term ''solenoid'' was coined in 1823 by André-Marie Ampère. The helical coil of a solenoid does not necessarily need to revolve around a straight-line axis; for example, William Sturgeon's electromagnet of 1824 consisted of a solenoid bent into a horseshoe shape (not unlike an arc spring). Solenoids provide magnetic focusing of electrons in vacuums, notably in television camera tubes such as vidicons and image orthicons. Electrons take helical paths within the magnetic field. These solenoids, focus coils, surround nearly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inductance
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the current, and follows any changes in current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction. This induced voltage created by the changing current has the effect of opposing the change in current. This is stated by Lenz's law, and the voltage is called '' back EMF''. Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. It is a proportionality factor that depends on the geometry of circuit conductors and the magnetic permeability of nearby materials. An electronic component designed to add inductance to a circuit is called an inductor. It typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HathiTrust
HathiTrust Digital Library is a large-scale collaborative repository of digital content from research libraries including content digitized via Google Books and the Internet Archive digitization initiatives, as well as content digitized locally by libraries. History HathiTrust was founded in October 2008 by the twelve universities of the Committee on Institutional Cooperation and the eleven libraries of the University of California. The partnership includes over 60 research libraries across the United States, Canada, and Europe, and is based on a shared governance structure. Costs are shared by the participating libraries and library consortia. The repository is administered by the University of Michigan. The executive director of HathiTrust is Mike Furlough. The HathiTrust Shared Print Program is a distributed collective collection whose participating libraries have committed to retaining almost 18 million monograph volumes for 25 years, representing three-quarters of HathiT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edison Institute
The Henry Ford (also known as the Henry Ford Museum of American Innovation and Greenfield Village, and as the Edison Institute) is a history museum complex in the Detroit suburb of Dearborn, Michigan, United States. The museum collection contains the presidential limousine of John F. Kennedy, Abraham Lincoln's chair from Ford's Theatre, Thomas Edison's laboratory, the Wright Brothers' bicycle shop, the Rosa Parks bus, and many other historical exhibits. It is the largest indoor–outdoor museum complex in the United States and is visited by over 1.7 million people each year. It was listed on the National Register of Historic Places in 1969 as Greenfield Village and Henry Ford Museum and designated a National Historic Landmark in 1981 as "Edison Institute". Museum background Named for its founder, the automobile industrialist Henry Ford, and based on his efforts to preserve items of historical interest and portray the Industrial Revolution, the property houses homes, machinery, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmholtz
Hermann Ludwig Ferdinand von Helmholtz (31 August 1821 – 8 September 1894) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The Helmholtz Association, the largest German association of research institutions, is named in his honor. In the fields of physiology and psychology, Helmholtz is known for his mathematics concerning the eye, theories of vision, ideas on the visual perception of space, color vision research, the sensation of tone, perceptions of sound, and empiricism in the physiology of perception. In physics, he is known for his theories on the conservation of energy, work in electrodynamics, chemical thermodynamics, and on a mechanical foundation of thermodynamics. As a philosopher, he is known for his philosophy of science, ideas on the relation between the laws of perception and the laws of nature, the science of aesthetics, and ideas on the civilizing power of scie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Coil
An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in devices such as electric motors, generators, inductors, electromagnets, transformers, and sensor coils. Either an electric current is passed through the wire of the coil to generate a magnetic field, or conversely, an external ''time-varying'' magnetic field through the interior of the coil generates an EMF (voltage) in the conductor. A current through any conductor creates a circular magnetic field around the conductor due to Ampere's law. The advantage of using the coil shape is that it increases the strength of the magnetic field produced by a given current. The magnetic fields generated by the separate turns of wire all pass through the center of the coil and add ( superpose) to produce a strong field there. The more turns of wir ... [...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, Florida, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetomotive Force
In physics, the magnetomotive force (mmf) is a quantity appearing in the equation for the magnetic flux in a magnetic circuit, often called Ohm's law for magnetic circuits. It is the property of certain substances or phenomena that give rise to magnetic fields: \mathcal = \Phi \mathcal , where is the magnetic flux and \mathcal is the reluctance of the circuit. It can be seen that the magnetomotive force plays a role in this equation analogous to the voltage in Ohm's law: , since it is the cause of magnetic flux in a magnetic circuit: # \mathcal = NI where is the number of turns in the coil and is the electric current through the circuit. # \mathcal = \Phi \mathcal where is the magnetic flux and \mathcal is the magnetic reluctance # \mathcal = HL where is the magnetizing force (the strength of the magnetizing field) and is the mean length of a solenoid or the circumference of a toroid. Units The SI unit of mmf is the ampere, the same as the unit of current (analogo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gilbert (unit)
The gilbert (symbol: Gb) is an obsolete unit used in practical cgs and CGS-EMU systems to measure magnetomotive force. The unit is named for English physicist William Gilbert. Definition: *1 Gb = (1/4π) Bi-turn Conversion to the corresponding quantity in the SI, with the unit ampere-turn The ampere-turn (A⋅t) is the MKS (metre–kilogram–second) unit of magnetomotive force (MMF), represented by a direct current of one ampere flowing in a single-turn loop in a vacuum. " Turns" refers to the winding number of an electrical ...: *1 Gb ≘ (10/4π) A-turn ≈ 0.7957747 A-turn *1 A-turn ≘ 4π × 10−1 Gb References {{CGS units Magnetism Units of measurement Centimetre–gram–second system of units ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
