101. Magnet The term magnetism was coined to explain the phenomenon whereby The magneticfield of a magnet is easily made visible by means of iron filings which http://www.newi.ac.uk/buckleyc/magnet.htm

MAGNETISM Author: David Harrison School of Education and Humanities Athrofa Addysg Uwch Gogledd Ddwyrain Cymru North East Wales Institute of Higher Education Wrexham, NORTH WALES Updated: These notes have been written to support your learning. They are not a susbtitute for attending the lectures. At the lectures you will see demonstrations, carry out simple experiments, discuss the underlying physical process in greater depth and obtain lecture diagrams not included in these notes, in order to complete your learning experience. There is a story that a Cretan shepherd by the name of Magnés , whilst tending sheep on the slopes of Mount Ida, found that his iron tipped crook and the nails of his boots were attracted to the ground. To find the source of the attraction he dug up the ground to find stones that we now refer to as lodestones (also spelled loadstone; lode means to lead or to attract) which contain magnetite , a natural magnetic material Fe O . The story may be apocryphal but the earliest discovery of the properties of lodestone was either by the Greeks or Chinese. Pliny the Elder (23-79 AD Roman) wrote of a hill near the river Indus that was made entirely of a stone that attracted iron.

102. Understanding Magnetism And Degaussing Methods The field levels due to residual magnetism in turbomachinery occur not from designbut from manufacturing, testing, and environmental causes. http://www.gaussbusters.com/ppm93.html

Principles of Magnetism and Stray Currents in Rotating Machinery By Paul I. Nippes, P.E., President Magnetic Products and Services, Inc. Introduction This paper presents a collection of information that should be useful for understanding magnetism in machinery. It can also be used as a reference guide for engineers and technicians regarding the principles of magnetism and how to measure and remove it. Delving briefly into some of the effects of magnetism, such as stray currents, the paper includes traces of measured shaft voltages. A table is included which shows acceptable levels of magnetism in turbomachinery, based upon field experience. Basic Concepts and Definitions A magnetic field can be represented by lines of induction or flux lines. These lines are invisible and are produced by magnetized material or by electrical currents. Magnetic fields are electrical in nature, and the magnetic field caused by a long straight line of current is simulated in Figure 1. The flux lines are continuous and exist in closed loops. A unit of magnetic flux is called a Maxwell (a line). The magnetic flux density (B) at any point is defined as the number of lines passing through an area, which is perpendicular to the direction of the flux lines. The magnetic flux density (B) is called a gauss (the number of lines per square centimeter), which is a vector quantity (a magnitude and direction at any point). The unit of flux density (B) is the gauss, which corresponds to one line per square centimeter (or 6.54 lines per square inch).

103. Magnetismofplanets magnetism of the Planets. The Earth. The Earth has a magnetic field. Compasses lineup with the magnetic field of the earth. The magnetic field has a north http://www.exo.net/~pauld/activities/magnetism/magnetismofplanets.html

Magnetism of the Planets The Earth The Earth has a magnetic field. Compasses line up with the magnetic field of the earth. The magnetic field has a north and a south pole. It is called a dipole field. The north magnetic pole is located just off the coast of Antarctica (yes, the north magnetic pole is located near the south geographic pole.) Here is a space photo of the Northern and Southern Auroras of the earth superimposed on a model of earth. The magnetic field of the earth interacts with charged particles from the sun to create auroras circling the polar regions The magnetic field of the earth is made by a billion ampere electric current which circulates within the liquid metal of the outer core of the earth. (The liquid metal outer core stretches from the solid metal inner core about a quarter of the radius of the earth to the rocky mantle which begins 1/2 way from the core to the surface.) When molten rocks which contain iron, cool in the presence of a magnetic field they record the magnetic field direction. We can look at the magnetic field recorded in the rocks and find out about the magnetic field of the earth in the past, the paleomagnetic field. The paleomagnetic field shows that the magnetic field of the earth has flipped its direction many times. The flipping of the poles occurs after times of hundreds of thousands of years. It does not reverse on a regular basis but reverses chaotically.

104. Geotimes - May 2004 - Deciphering Planetary Magnetism Deciphering planetary magnetism As Voyager 2 neared Uranus in January 1986, NASAscientists They expected the field to be much like those of Jupiter, http://www.geotimes.org/may04/NN_neptune.html

News Notes Planetary geology Deciphering planetary magnetism In the March 11 issue of Nature Bolstering this hypothesis, the new model shows that a dynamo formed by the interaction of two liquids, as opposed to a solid and a liquid as in Earth, could produce smaller scale magnetic fields with multiple poles. Additionally, the lack of differential rotation between the two fluid layers would inhibit the alignment of the magnetic field with the axis of rotation, thus causing the tilted poles found by Voyager 2. Nature commentary. To create the dynamo, Stanley and Bloxham modeled a planet where one-sixth of the radius of the dynamo region is a rocky nonconductive core, one-half is a nonconvecting stably stratified liquid, and the top one-third is a convecting liquid. In addition to the radius, the researchers could vary other conditions, including how vigorously the convection is being driven and the stability of the interior. How the model responds will give researchers more information about the interior structures of the distant bodies. The findings may also play a role in future orbiter missions to the giant gas planets to better measure their magnetic fields, which would help determine the locations of their dynamos.

105. Intergalactic Magnetism Runs Deep And Wide: Science News Online, May 6, 2000 The stronger the magnetism there or the denser the gas that the field pervades,the more the field rotates the light s polarization. http://www.sciencenews.org/articles/20000506/fob5.asp

Science News Books. Subscribe to Science News ... Science News for Kids Math Trek Completing Latin Squares Food for Thought Chocolate Therapies (with recipe for Janet’s Chocolate Medicinal Mousse Pie) Science Safari A Hubble Decade TimeLine 70 Years Ago in Science News Science News e-LETTER. ... Week of May 6, 2000; Vol. 157, No. 19 , p. 294 Intergalactic magnetism runs deep and wide Peter Weiss Hunting for magnetic energy in intergalactic space, researchers have found an unexpected motherlode of it. Both in the gaps between galaxies that are clustered and in the lonelier neighborhoods outside those clusters, magnetic fields are remarkably strong, a scientific team reports. Computer-enhanced radio sky near the Coma cluster (arrow) shows intergalactic magnetic fields (red, weakest; blue, strongest) and more distant radio sources (compact blue dots). Kronberg et al As their hunt widens, the scientists find that they are detecting more extensive fields, says Philipp P. Kronberg of the University of Toronto, leader of the decades-long search. Kronberg reported the results April 29 at an American Physical Society meeting in Long Beach, Calif. This is evidence of a tremendous energy source that astronomers have overlooked, comments theorist Stirling A. Colgate of Los Alamos (N.M.) National Laboratory. At the meeting, he argued that enormous dynamos powered by black holes have cranked up these intergalactic magnetic fields. Other researchers suspect instead that the fields arose during the early history of the universe.

106. Vector » Browse By Classification Records 1 to 3 of 3 in Fundamental areas of phenomenology » Electricity andmagnetism; fields and charged particles. Chapter 6 The romance of electricity http://vector.iop.org/index.cfm?action=browse.home&type=in&dir=A4000/A4100

107. Vector » Browse By Classification properties » Magnetic properties and materials » General theory and models ofmagnetic ordering » Crystalfield theory and spin Hamiltonians (magnetism) http://vector.iop.org/index.cfm?action=browse.home&type=in&dir=A7000/A7500/A7510

108. Untitled Document The origin and evolution of Cosmic magnetism Strong field tests of gravity This ``cosmic magnetism cannot be ascribed to permanent magnets like the http://www.skatelescope.org/pages/science_genp_key_magnf.htm

Key science projects Cradle of Life Probing the Dark Ages The origin and evolution of Cosmic Magnetism Strong field tests of gravity using pulsars and black holes ... Galaxy evolution, cosmology and dark energy The origin and evolution of Cosmic Magnetism Everybody knows that the Earth is magnetic. The Earth's magnetic field acts as a shield which protects us against energetic solar and interstellar particles; the Earth's magnetism is vital for navigation, both for humans and for many other species too. An image of the Sun's corona, taken in Nov 1999 by the Transition Region and Coronal Explorer (TRACE) satellite. The giant loops of gas seen arching above the Sun's surface delineate the patterns made by invisible magnetic fields. TRACE is a mission of the Stanford-Lockheed Institute for Space Research, and is part of the NASA Small Explorer program. It has been well-established that stars, planets, galaxies and even diffuse interstellar gas are all also magnetic. This ``cosmic magnetism'' cannot be ascribed to permanent magnets like the ones which come in a science kit, but to motions of huge, thin clouds of gas which are electrically charged. Cosmic magnetism spans an enormous range in its strength, varying by a factor of a hundred billion billion between the weak magnetic fields in interstellar space and the extreme magnetism found on the surface of collapsed stars. Because these cosmic magnetic fields are all-pervasive, they play a vital role in controlling how celestial sources form, age and evolve.

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