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Topic: Torsion balance

	torsion balance on Encyclopedia.com
		The torsion balance consists essentially of a wire or thread attached at one end and arranged in such a way that a force applied at the other, or free, end tends to twist it out of shape.
		Torsion balances are used to measure small electric, magnetic, and gravitational forces.
		The invention of the torsion balance is commonly credited to the English geologist John Michell, who made his instrument c.1750, and to the French physicist Charles A. de Coulomb, who independently devised such a balance c.1777.
	www.encyclopedia.com /html/t1/torsionb.asp (423 words)

	BALANCE - Definition (Site not responding. Last check: 2007-10-19)
		Another form is that of the Roman balance, our steelyard, consisting of a lever or beam, suspended near one of its extremities, on the longer arm of which a counterpoise slides.
		{Balance electrometer}, a kind of balance, with a poised beam, which indicates, by weights suspended from one arm, the mutual attraction of oppositely electrified surfaces.
		{Balance valve}, a valve whose surfaces are so arranged that the fluid pressure tending to seat, and that tending to unseat the valve, are nearly in equilibrium; esp., a puppet valve which is made to operate easily by the admission of steam to both sides.
	www.hyperdictionary.com /dictionary/balance (1072 words)

	Torsion bar experiment - Wikipedia, the free encyclopedia
		In physics, the purpose of the torsion bar experiment is to estimate the gravitational constant.
		The torsion bar experiment was originally proposed by John Michell, who constructed a torsion bar apparatus, but Michell died without completing the experiment.
		From the twisting force in the wire and the known masses of the spheres, Cavendish was able to calculate the value of the gravitational constant.
	en.wikipedia.org /wiki/Torsion_bar_experiment (323 words)

	Sphæra issue no. 6: article 6
		The torsion balance electrometer was developed by Charles Augustin Coulomb (1736-1806) in a series of experiments carried out in Paris in the years before and during the Revolution and culminating in his prize-winning memoir purporting to demonstrate the inverse square law of electrostatic force.
		The difficulty in using the torsion balance and the problematic nature of the replication of Coulomb's experiment was illustrated in 1992 in a programme carried out by Peter Heering at the Department of Physics in the University of Oldenburg.
		The prevalence of the balance as an ornament in nineteenth-century laboratories was certainly due in part to its association with Coulomb as an authority, but its popularity must also have rested to a significant extent on the promise for future development that it came to represent.
	www.mhs.ox.ac.uk /sphaera/issue6/articl6.htm (1153 words)

	doc15
		Since a torsion field is identical to the transverse spin polarization of the physical vacuum, and a gravitational field is identical to the longitudinal spin polarization of the physical vacuum [1], then some properties of torsion fields are identical to the properties of gravitational fields.
		Torsion balances were employed in experiments conducted by N.P.Myshkin at the end of the IXX century, and later were employed in the experiments of N.A.Kozyrev and others.
		For instance, if the torsion balances are subjected to the influence of a "right" torsion field, and the indicator moves in one direction, then after influencing the torsion balance with a "left" torsion field, the indicator will move in the opposite direction.
	www.amasci.com /freenrg/tors/doc15.html (1612 words)

	torsion balance -- Encyclopædia Britannica
		The torsion balance consists essentially of two small masses at different elevations that are supported at opposite ends of a beam.
		The latter is suspended from a wire that undergoes torsion...
		His study of the Earth's gravitational field—which led to his development of the Eötvös torsion balance, long unsurpassed in precision—resulted in proof that inertial mass and gravitational mass are equivalent, later a major principle of Albert Einstein's general theory of relativity.
	www.britannica.com /eb/article-9072987?tocId=9072987 (825 words)

	NCEMO - Torsion Balance & Drive Coil
		Since the Balance is sensitive to the sum of all of the magnetic fields to which it is exposed and it is at its zero position, the magnetic field generated by the Drive Coil set is a direct measure of the other magnetic fields.
		A Torsion Balance Magnetometer consists of a strong Sensor Magnet rigidly attached to a mirror and suspended by a strong fiber which constrains its motion to a single degree of freedom, rotation about the long axis of the fiber.
		The maximum deflection is obtained at the so-called "resonant frequency" of the Balance and is a function of the sensor magnet and mirror masses, their radial location relative twist axis as defined by the nylon thread, and the "springiness" of the nylon thread.
	www.xtrsystems.com /magnetometer/coil (1300 words)

	Eotvos and STEP
		A torsion balance rotating around a horizontal axis for measuring the vertical gradient of g was also abandoned later.
		The major obstacle in the way of increasing the sensitivity of the torsion balance was that the fibre had to be strong enough to hold the weight, but then its restoring torque was very hard to reduce.
		The Eötvös balance was the first instrument for gravitational gradiometry, that is for the measurement of the very local properties of the shape of the equipotential surfaces of earth.
	www.kfki.hu /~tudtor/eotvos1/stepcikk.html (2717 words)

	Torsion Balance
		Constructed in 1902 in Germany, it is the progenitor of torsion balances used extensively in the early stages of petroleum exploration during the 1920's and 30's.
		Up to its demise in about 1938, the torsion balance contributed exclusively or partially to the discovery of 79 oil fields in the Gulf coastal region of Texas and Louisiana where it was principally applied in oil exploration.
		The torsion balance derives its name from the gravity measuring element which consists of two parallel weighted beams, each suspended by a wire at its center.
	www.mssu.edu /seg-vm/TorBal.html (662 words)

	The UW Eot-Wash Group (Site not responding. Last check: 2007-10-19)
		Eötvös pioneered the use of torsion balances for testing the principle of equivalence, i.e.
		Torsion balance experiments in general measure some quantity by detecting a torque on a hanging pendulum; the torque is produced by some field interacting with a dipole or higher order moment.
		One very nice feature of torsion balance experiments is that they are insensitive to slight differences in the masses or moment arms of the test bodies.
	www.npl.washington.edu /eotwash (1343 words)

	Torsion Balance
		Constructed in 1902 in Germany, it is the predecessor of torsion balances used extensively in the early stages of petroleum exploration in the 1920's and 30's.
		Until its demise in 1938, the torsion balance contributed exclusively or partially to the discovery of 79 oil fields in the Gulf coastal region of Texas and Louisiana where it was principally applied in oil exploration.
		The torsion balance derives its name from the two parallel weighted beams, each suspended by a wire at its center, that sense variations in the earth's gravity.
	www.mssu.edu /seg-vm/pict0349.html (663 words)

	Non-classical Pendula
		By operating with the restoring torques of torsion and gravity in opposition, a double-well potential function is appropriate to the description of the motion at lower levels of the motion.
		The tiltmeter is a torsion pendulum having some similarities to the torsion-gravity pendulum, however it is designed to operate away from the double well of the latter.
		The amount of gravitational opposition to the torsion is controlled by the angle of inclination of the torsion wire with respect to the local gravitational field.
	physics.mercer.edu /petepag/pend.htm (2337 words)

	MEASURING THE GRAVITATIONAL CONSTANT, G (Site not responding. Last check: 2007-10-19)
		The torsion fiber is a stainless steel wire with a diameter of 0.003 inch (0.0012 cm) and a length of approximately 1.75 m.
		Thus, an attempt was made to build a large-scale version of the traditional torsion balance apparatus which would be economically feasible and provide a clearly visible demonstration of the gravitational attraction between objects of ordinary mass.
		In practice, the torsion balance is allowed to come into equilibrium with the two bags of sand "kitty-corner" from each other, as shown in the diagram.
	www.iit.edu /~smile/ph8615.html (599 words)

	Cavendish Experiment (Site not responding. Last check: 2007-10-19)
		At equilibrium, the gravitational torque on the dumbbell is balanced by the torque
		The actual balance is enclosed in a metal case with glass windows to protect the torsion balance from air currents while allowing the laser beam to bounce from the mirror.
		The various components of the experiment are: the torsion balance, the laser, and a ruler, which acts as the screen.
	physics.usask.ca /~kolb/p404/cavendish (678 words)

	Henry Cavendish: Weighing the Earth
		The usual torsion balance consists of a 'dumbbell' (two masses connected by a horizontal rod) suspended by a very thin fiber.
		His balance was constructed from a 6-foot wooden rod suspended by a metal fiber, with 2-inch-diameter lead spheres mounted on each end of the rod.
		Use the densest objects you can obtain for the ends of the balance beam and as test masses: lead sinkers, steel balls, plutonium hemispheres, etc. Density is important because the gravitational force varies as the inverse square of the distance between the centres of mass of two objects.
	www.juliantrubin.com /bigten/cavendishg.html (1264 words)

	Precision Torsion Balance
		Usage: This balance is designed for the rapid determination of weights of small objects (<1.5 gm) to a reasonably high precision (±0.25 mg).
		Balance is achieved through aligning a floating, angled, needle against a broken line adjacent to a small mirror.
		A rectangle of aluminum foil of precisely equal mass is hung on the opposite hook through a punched hole to act as a counter weight.
	www.humboldt.edu /~scimus/HSC.54-70/Descriptions/BalRoller.htm (484 words)

	Active Skim View of: Chapter XI. Gravity Measurements with the Eotvos Torsion Balance
		Normally, within the system of the Eotvos torsion balance the level surfaces near each weight are not horizontal with respect to the center of gravity of the balance, and as the only movement that is possible for the weight is horizontal rotation, it tends to fall horizontally through the inclined level surfaces.
		The Eotvos torsion balance is a special type of the Coulomb balance if' the assumption is made that within the very small area of the working system of' the Lotvos torsion balance the curvature of' all level surfaces is identical.
		In field work with the Eotvos torsion balance, levels are run out to 20, 50, or 100 meters from the instrument, the distance depending on the irregularity and relief of the topography, and the effects on the gradient and differential curvature are calculated by simple tabular forms.
	www.nap.edu /nap-cgi/skimit.cgi?isbn=ARC000033&chap=167-190 (930 words)

	BIRMINGHAM GRAVITATION GROUP.
		We rediscovered that the restoring torque of a strip, whose thickness is much less than its width, is essentially determined by the weight of the suspended torsion bob rather than the elastic properties of the material from which the strip is made.
		Accurate timing of the period of oscillation together with a calculation of the moment of inertia of the bob are used to determine G. The torsion strip design effectively eliminates the effects of anelasticity on this measurement.
		The third method uses the change in the oscillation period of the torsion balance as the source masses add or subtract from the restoring torque of the torsion strip.
	www.sr.bham.ac.uk /gravity/rh,c,5.html (488 words)

	MSN Encarta - Search Results - torsion balance
		Another important development was Coulomb’s measurement of the strength and behavior of the electrical force between two charge balls.
		Torsion, twisting strain produced when a torque is applied to an object.
		For example, torsion is the strain experienced by a length of wire when a...
	encarta.msn.com /torsion+balance.html (142 words)

	Eötvös the Scientist
		One was the strict physical theoretical aspect of the process, and the other, the actual construction of an unbelievably sensitive instrument, the famous torsion balance for this research work.
		From the results of his torsion balance survey it was established that parallel to the axis of the lake ran a tectonic line.
		In 1916 on the initiative of Hugo Böckh, an eminent Hungarian geologist, torsion balance measurements were carried out in the region of Egbell (Gbely, Slovakia) where oil was produced from a recognized anticlinal structure.
	www.elgi.hu /museum/elatud_.htm (1740 words)

	The Torsion Balance (Site not responding. Last check: 2007-10-19)
		The first type was a light horizontal beam suspended on a torsion wire with platinum masses attached to either end, so that the masses were at the same level (Curvature Variometer).
		The second type has a platinum mass attached to one end of the horizontal beam, while on the other end a platinum cylinder hangs on a wire so that the second mass is at a lower level than the other one (Horizontal Variometer).
		The beam in both cases revolves around the torsion wire on a horizontal plane and is deflected from the torsionless position of the wire by the horizontal components of the gravity forces.
	www.elgi.hu /museum/tinga_.htm (607 words)

	PIRA 1L10.00 UNIV. GRAVITATIONAL CONSTANT (Site not responding. Last check: 2007-10-19)
		The Cavendish balance is driven into resonance by swinging the external mass.
		Modify the Leybold Cavendish balance with a electromagnetic servosystem of damping that reduces the settling time to a few minutes.
		The reflected laser light from the Cavendish balance falls on a two-element photodiode mounted on a strip chart recorder with appropriate electronics to keep the spot centered on the diode.
	www.physics.ncsu.edu /pira/1mech/1L10.html (250 words)

	The Physics Classroom
		The value of G was not experimentally determined until nearly a century later by Lord Henry Cavendish using a torsion balance.
		When the long rod becomes twisted, the torsion of the wire begins to exert a torsional force which is proportional to the angle of rotation of the rod.
		Once the torsional force balanced the gravitational force, the rod and spheres came to rest and Cavendish was able to determine the gravitational force of attraction between the masses.
	www.physicsclassroom.com /Class/circles/U6L3d.html (401 words)

	[No title] (Site not responding. Last check: 2007-10-19)
		My entry in the this category in the 2001 contest in New Orleans began with the desire to build a timepiece with a chronometer escapement (sometimes also called a detent escapement.) These escapements are known for their accuracy, being used in the marine chronometers which aided navigation in the open seas.
		The period of the balance wheel depends on its mass and the strength of its balance spring.
		The huge variation in possible balances and springs would make building a balance wheel to fit a given gear train a tedious task -- one which could be only done by trial and error.
	www.onlineclockbuilding.com /gallery/bullart.doc (964 words)

	Bloat, Torsion \| GREATDANELADY.COM
		Bloat and torsion may appear to be triggered by one event when in reality it is a condition that has been building due to a number of circumstances.
		Exercise is important in the elimination of stress for humans as well as animals, and dogs that are kenneled and caged without adequate exercise for muscle/bone development as well as for psychological reasons (boredom and inertia) are primary candidates for these diseases.
		There may be a possible connection between bloat and torsion and inadequate amounts of or an absence of sulfur and micronutrients in the processed canine diet.
	www.greatdanelady.com /articles/bloat_and_torsion_is_nutrition_a_factor.htm (5699 words)

	Handbook of Texas Online: OIL EXPLORATION
		The torsion balance was one of the earliest geophysical instruments used in the exploration for salt domes along the Texas Gulf Coast.
		Eoetvoes's torsion balance and instruments like it made use of the earth's gravitational field and the way the field varied according to differences in mass distribution near the earth's surface.
		The field balance is used on the earth's surface to measure magnetism in specific locations.
	www.tsha.utexas.edu /handbook/online/articles/view/OO/doo15.html (2132 words)

	BIPM - Newtonian constant of gravitation
		The BIPM is engaged in the determination of the Newtonian constant of gravitation G using a novel torsion balance.
		The principal novelties of the BIPM torsion balance are:
		a torsion strip, rather than a torsion wire, to give a much improved stability; this is because the restoring torque of a heavily loaded strip is set mostly by its dimensions and the weight of the suspended object and is practically independent of the material properties of the strip;
	www.bipm.fr /en/scientific/mass/research_mass/big_g.html (317 words)

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