Ferromagnetism - a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. It is responsible for most of the magnetic behavior encountered in everyday life, and is the basis for all permanent magnets (as well as the metals that are attracted to them). Some examples of ferromagnetic materials are iron, cobalt, nickel, and gadolinium. Physical origin The property of ferromagnetism is due to the direct influence of two effects from quantum mechanics: spin and the Pauli exclusion principle. The spin of an electron has a magnetic dipole moment and creates a magnetic field. (The classical analogue of quantum-mechanical spin is a spinning ball of charge, but the quantum version has distinct differences, such as the fact that it has discrete up/down states that are not described by.
Diamagnetism - Diamagnetism Diamagnetism is a very weak form of magnetism that is only exhibited in the presence of an external magnetic field. It is the result of changes in the orbital motion of electrons due to the external magnetic field. The induced magnetic moment is very small and in a direction opposite to that of the applied field. When placed between the poles of a strong electromagnet, diamagnetic materials are attracted towards regions where the magnetic field is weak. Diamagnetism is found in all materials, however because it is so weak it can only be observed in materials that do not exhibit other forms of magnetism. An exception to the "weak" nature of diamagnetism occurs with the rather large number of materials that become superconducting, something that usually happens at lowered temperatures..
School science experiment--Indian rope trick (magnetism) - science experiment--Indian rope trick (magnetism) Experiment setup This is a How-to about a School science experiment--Indian rope trick (magnetism). This is a good demonstration that is used in schools to teach the idea of magnetic materials. It can be fiddly to set up, but it's worth the effort. Table of contents showTocToggle("show","hide") 1 Materials 2 Method 3 How does it work? 3.1 See Also Materials Clamp stand Magnet Paper clip Cotton Sticky tape Samples of materials to insert in the gap Method Clamp the magnet in the clamp stand. Tie some cotton onto a steel paperclip and allow the paperclip to stick to the magnet. Gently pull the cotton down so that there is an air space between the paperclip and the magnet, and then stick it to the bench with.
Magnetism - Magnetism In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. Magnetism arises whenever electrically charged particles are in motion. Some well known materials that exhibit magnetic properties are iron, some steels, and the mineral lodestone. All materials are influenced to one degree or another by the presence of a magnetic field, although in some cases the influence is too small to detect without special equipment. Magnetic forces are fundamental forces that arise due to the movement of electrically charged particles. Maxwell's equations describe the origin and behavior of the fields that govern these forces (see also Biot-Savart's Law). For the case of electric current moving through a wire, the resulting field is directed according to the "right.
James Clerk Maxwell - received the Rumford medal from the Royal Society in 1860. The instruments which he devised for these investigations were simple and convenient, but could not have been thought of for the purpose except by a man whose knowledge was co-extensive with his ingenuity. In 1856, Maxwell was appointed to the chair of Natural Philosophy in Marischal College, Aberdeen, which he held until the fusion of the two colleges there in 1860. He obtained in 1859 the Adams prize in Cambridge for an original and powerful essay, “On the Stability of Saturn’s Rings”, in which he concluded the rings could not be completely solid or fluid. Maxwell demonstrated stability could be reached only if the rings consisted of numerous small solid particles. He also mathematically disproved the nebular hypothesis (which stated that.
James Glaisher - and Trinity College, Cambridge, Glaisher was an assistant at the Royal Greenwich Observatories at Cambridge and Greenwich, and Superintendent of the Department of Meteorology and Magnetism at Greenwich for thirty-four years. In 1845, Glaisher published his dew point tables, for the measurement of humidity. Glaisher was a founder member of the Meteorological Society (1850), and the Aeronautical Society of Great Britain (1866). He is most famous, however, as a pioneering balloonist. Between 1862 and 1866, usually with Henry Tracey Coxwell as his co-pilot, Glaisher made numerous ascents in order to measure the temperature and humidity of the atmosphere at its highest levels. One one ascent in 1862, he broke the world record for altitude, but passed out before a reading could be taken. Estimates suggest that he rose to approximately 7.
James Tilly Matthews - teams of "magnetic spies" had infiltrated England and were preparing to use 'air looms' (a type of mind control machine that used "animal magnetism" and mesmerism) to overthrow the government. Matthews also believed he was subject to control by the air loom, which he believed was operated by the sinister 'air loom gang' consisting of seven members led by a man called "Bill, or the King". He was convinced that the gang were trying to destroy him by using "torture-at-a-distance" which included torments such as "foot-curving, lethargy-making, spark-exploding, knee-nailing, burning out, eye-screwing" and other fantastical effects. John Haslam's illustration of James Tilly Matthews' Air Loom His delusions got him admitted to Bedlam psychiatric hospital in 1797 where his family argued for his release. Two distinguished physicians, Drs Birkbeck and Clutterbuck, subsequently.
Jean Baptiste Biot - who in the early 1800s studied the relationship between electrical current and magnetism (see Biot-Savart's Law), as well as the polarisation of light passing through chemical solutions. He was the first person to discover the optical difference of mica, and therefor the mineral biotite was named after him. In 1804 he made a hot-air balloon ascent with Joseph Gay-Lussac to a height of five kilometres in an early investigation of the Earth's atmosphere..
Johannes Kepler - the universe which shows a cube, inside a sphere, with a tetrahedron inscribed in it, another sphere inside it with a dodecahedron inscribed, a sphere with an icosahedron inscribed inside, and finally a sphere with an octahedron inscribed. Each of these celestial spheres had a planet embedded within them, and thus defined the planet's orbit. On October 17, 1604, Kepler observed that an exceptionally bright star had suddenly appeared in the constellation Ophiuchus. (It had appeared on October 9 previous.) The appearance of the star, which Kepler described in his book De Stella nova in pede Serpentarii, provided further evidence that the cosmos was not changeless; this was to influence Galileo's argument. It has since been determined that the star was a supernova, the second in a generation, called Kepler's Star..
John Monash - a professionally trained officer, was free of the antiquated doctrines of many First World War officers. He believed in the co-ordinated use of infantry, aircraft, artillery and tanks. He wrote: The true role of infantry is not to expand itself upon heroic physical effort, not to wither away under merciless machine-gun fire, not to impale itself on hostile bayonets, but on the contrary, to advance under the maximum possible protection of the maximum possible array of mechanical resources, in the form of guns, machine-guns, tanks, mortars and aeroplanes; to advance with as little impediment as possible; to be relieved as far as possible of the obligation to fight their way forward. At the Battle of Hamel Hill on 4 July 1918 Monash applied this doctrine, and led his troops to won.
John Hopkinson - became famous through his theoretical en practical work on the application of electricity and magnetism in devices like a dynamo and electromagnets. [1] The magnetic equivalent of Ohm's law is named after him. Hopkinson's law, Maxwell's laws.
John Tyndall - He passed from a national school in Co. Carlow to a minor post (1839) in the Irish ordnance survey, thence (1842) to the English survey, attending mechanics' institute lectures at Preston in Lancashire. He then became for a time (1844) a railway engineer, and in 1847 a teacher at Queenwood College, Hants. Thence with much spirit, and in face of many difficulties, he betook himself, with his colleague Edward Frankland, to the university of Marburg (1848-1851), where, by intense application, he obtained his doctorate in two years. His inaugural dissertation was an essay on screw-surfaces. Tyndall's first original work in physical science was in his experiments with regard to magnetism and diamagnetic polarity, on which he was chiefly occupied from 1850 to 1855. While he was still lecturing on natural philosophy.
John Hasbrouck van Vleck - at Harvard, Van Vleck developed fundamental theories on the quantum mechanics of magnetism and on molecular bonding (ligand field theory). For his contributions to the understanding of electrons in magnetic, noncrystalline solids, Van Vleck was awarded the 1977 Nobel Prize in Physics, along with Philip W. Anderson and Sir Nevill Mott. External Links John Hasbrouck van Vleck.
Justinus Kerner - Hauffe, the daughter of a forester in Prevorst, a somnambulist and clairvoyante, arrived; she forms the subject of Kerner's famous work Die Seherin von Prevorst, Erffnungen ber das innere Leben des Menschen und uber das Hineinragen einer Geisterwelt in die unsere (1829; 6th ed., 1892). In 1826 he published a collection of Gedichte which were later supplemented by Der letzte Blütenstrauß (1852) and Winterbluten (1859). Among others of his well-known poems are the charming ballad Der reichsle Furst; a drinking song, Wohlauf, noch getrunken, and the pensive Wanderer in der Sägemühle. In addition to his literary productions, Kerner wrote some popular medical books, dealing with animal magnetism, a treatise on the influence of sebacic acid on animal organisms, Das Fettgift die Fettsäure und ihre Wirkung auf den tierischen Organismus (1822); a.
Intellectual history of time - the sun on the horizon. Isochronous time was seen as a problem more than a solution, because people's lives still revolved around the light needed to see. The acceptance of isochronous time had to wait until 1879 when the light bulb was invented. But the clocks were still aligned with the rise of the sun. It took the steam enginge to completely divorce time from the sun. Invention of the locomotive in 1830, time had to be synchronized across vast distances in order to organize the train schedules. This eventually led to the development of time zones, and, of course, global isochronous time. The isochronous clock changed our lives. The all-powerful business day revolved around it - the bars close at 2:00, and appointments were no longer 'within the hour', but.
Hans Christian Orsted - influenced by the thinking of Immanuel Kant. In 1820 he discovered the relationship between electricity and magnetism in a very simple experiment. He demonstrated that a wire carrying a current was able to deflect a magnetised compass needle. Ørsted did not suggest any satisfactory explanation of the phenomenon, nor did he try to represent the phenomenon in a mathematical framework. In 1825 he made a significant contribution to chemistry by producing aluminum for the first time. See also: James Clerk Maxwell, physics..
Hendrik Lorentz - theory of James Clerk Maxwell to better explain the reflection and refraction of light. He was appointed professor of mathematical physics at the Univiersity of Leiden in 1878. During his time there he was primarily interested in a single theory to explain the relationship of electricity, magnetism, and light. Lorentz theorized that the atoms might consist of charged particles and suggested that the oscillations of these charged particles were the source of light. This was experimentally proven in 1896 by Pieter Zeeman, a pupil of Lorentz. In 1895 in an attempt to explain the Michelson-Morley experiment, Lorentz introduced the concept of local time (different time rates in different locations). He also proposed that bodies approaching the velocity of light contract in the direction of motion (see FitzGerald-Lorentz Contraction). (George FitzGerald had.
History of physics - destruction of most classical Greek philosophy (along with Greek and Roman art, literature and religious iconography) as heretical and pagan. In the Middle East, however, many Greek natural philosophers were able to find support in the newly created Arab Caliphate (Empire), and the Islamic scholars built upon previous work in medicine, astronomy and mathematics while developing such new fields as alchemy (chemistry). For example, the scholar Muhammad ibn Musa al-Khwarizmi gave his name to what we now call an algorithm, and the word algebra is derived from al-jabr, the beginning of the name of one of his publications in which he developed a system of solving quadratic equations, thus beginning Al-gebra. It is sometime assumed that the Islamic civilization simply preserved the older learning without any innovation. In astronomy, chemistry, and.
History of Parapsychology - of Renaissance magic (alchemy and the like). The period known as the Enlightenment followed in its wake, with its apex in the 18th century, and featured the ideas that life should be lead by reason as opposed to dogma or tradition, and the universe as a mechanistic, deterministic system that could eventually be known accurately and fully through observation, calculation, and reason. As such, the existence or activity of deities or supernatural agents was discounted, and so the beginnings of antagonism towards the existence of psi phenomena along with all forms of magical thinking. Franz Anton Mesmer (b 1734 - d 1815), a Viennese physycian, wanted to be considered a man of the Enlightenment. At the time, electricity and magnetism were thought of as invisible "fluids". Mesmer believed that he had.
Hui - assimilated into the surrounding population keeping only their distinctive religion. A totally different explanation is available for the Mandarin Chinese-speaking Yunnan and Northern Huis, whose ethnogenesis might be a result of the convergence of large number of Mongol, Turkic or other Central Asian settlers in these regions who formed the dominant stratum in the Mongol Yuan Dynasty. It was documented that a proportion of these nomad or military ethnic groups were originally Nestorian Christians who were later drawn to the strong magnetism of Islam, while under the sinicizing pressures of the Ming and Qing states. This explains the ethnonym "Hui", in close affinity with that of "Uygur", albeit Sinicized and contradistinctive from "Uygur" in usage. The ethnonym "Hui", though for a long time used as an umbrella term (at least since.
