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Topic: Galvanometer

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	Galvanometer - LoveToKnow 1911
		A ray of light being thrown on the mirror from a lamp the deflexions of the needle were observed by watching the movements of a spot of light reflected from it upon a fixed scale.
		The movable coil galvanometer has the great advantage that it is not easily disturbed by the magnetic fields caused by neighbouring magnets or electric currents, and thus is especially useful in the electrical workshop and factory.
		In the construction of a movable coil galvanometer, it is usual to intensify the magnetic field by inserting a fixed soft iron core in the interior of the movable coil.
	www.1911encyclopedia.org /Galvanometer (2114 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		The earliest galvanometer was reported by Johann (Johan) Schweigger of Nuremberg at the University of Halle on 16th September 1820.
		In some cases (the classical polygraph of movies or the electroencephalograph), the galvanometer is strong enough to move the pen while it remains in contact with the paper; the writing mechanism may be a heated tip on the needle writing on heat-sensitive paper or a fluid-fed pen.
		A galvanometer appeared in an episode (#12, season 2) of the television medical drama House to function as an electrocardiogram for a patient whose severe and extensive burns prevented use of the normal electrodes.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=galvanometer (1394 words)

	Galvanometers
		All galvanometers are based upon the discovery by Hans C. Oersted that a magnetic needle is deflected by the presence of an electric current in a nearby conductor.
		These meters were called tangent galvanometers because the tangent of the angle of deflection of the needle is proportional to the strength of the current in the coil (at this point in time it was impossible to construct a meter whose needle deflection was directly proportional to the current under measurement).
		One of the limitations of early galvanometers was that the length of the needle had to be kept very short in order to minimize the effects of the earth's magnetic field and reduce damping errors introduced by the mass of the needle itself.
	rd.business.com /index.asp?epm=s.1&bdcq=Galvanometer&bdcr=4&bdcu=http://www.sparkmuseum.com/GALV.HTM&bdcp=&partner=2662601&bdcs=nwuuid-2662601-6F201404-7BE9-50D6-97A9-0E54C670D393-ym (872 words)

	Tangent Galvanometer - Kimball
		- In the tangent galvanometer there is a circular coil having one or more turns of wire, at the center of which a magnetic needle is either balanced on a point or suspended by a fine fiber of silk or quartz.
		n case of a tangent galvanometer the magnetic force F due to the coil is expressed by IG.
		A tangent galvanometer in which the constant is determined in this way directly from measurements of the coil is known as a standard galvanometer.
	www.humboldt.edu /~scimus/Instruments/Elec-Kimball/TanGalKim.htm (526 words)

	GALVANOMETER - Online Information article about GALVANOMETER
		By the sensitiveness of the Movable needle galvanometer.
		metre from the mirror, when an electromotive force of one-millionth of a volt (microvolt) is applied to the terminals of the galvanometer; it may be otherwise expressed by stating the deflexion produced under the same conditions when a current of one microampere is passed through the coil.
		swing to the next succeeding swing, and a galvanometer of which the logarithmic decrement is large, is said to be highly damped.
	encyclopedia.jrank.org /GAG_GEO/GALVANOMETER.html (3026 words)

	Galvanometers
		Galvanometers were the first instruments used to determine the presence, direction, and strength of an electric current in a conductor.
		These meters were called tangent galvanometers because the tangent of the angle of deflection of the needle is proportional to the strength of the current in the coil (at this point in time it was impossible to construct a meter whose needle deflection was directly proportional to the current under measurement).
		One of the limitations of early galvanometers was that the length of the needle had to be kept very short in order to minimize the effects of the earth's magnetic field and reduce damping errors introduced by the mass of the needle itself.
	www.sparkmuseum.com /GALV.HTM (761 words)

	Galvanometer Summary
		In the case of a moving-mirror galvanometer, a mirror is attached to the coil, and illuminated with light.
		Galvanometer mechanisms are used to position the pens of analog chart recorders such as used for making an electrocardiogram.
		In some cases (the classical polygraph of movies or the electroencephalograph), the galvanometer is strong enough to move the pen while it remains in contact with the paper; the writing mechanism may be a heated tip on the needle writing on heat-sensitive paper or a fluid-fed pen.
	www.bookrags.com /Galvanometer (1365 words)

	galvanometer - Search Results - MSN Encarta
		Galvanometer, device used to measure small values of electric current.
		Galvanometers make use of the fact that an electric current flowing in a coil...
		Galvanometers are the main instruments used to detect and measure current.
	encarta.msn.com /galvanometer.html (123 words)

	Laws in electronics
		The mechanism of the galvanometer is so arranged that a small permanent magnet or electromagnet sets up a magnetic field that generates a force when current flows in a wire coil adjacent to the magnet.
		Galvanometers are usually named according to the magnitude of the currents they will measure.
		Ordinary galvanometers cannot be used for the measurement of an alternating current (AC), because the alternation of the current would produce deflection in both directions.
	library.thinkquest.org /C006657/electronics/laws.htm (1363 words)

	galvanometer - HighBeam Encyclopedia
		All galvanometers are based upon the discovery by Hans C. Oersted that a magnetic needle is deflected by the presence of an electric current in a nearby conductor.
		In the first galvanometers, a freely turning magnetic needle was hung in a coil of wire; in later versions the magnet was fixed and the coil made movable.
		The DC ammeter, an instrument for measuring direct current, often consists of a calibrated galvanometer through which the current to be measured is made to pass.
	www.encyclopedia.com /doc/1E1-galvanom.html (619 words)

	Tangent Galvanometer
		The tangent galvanometer was first described in an 1837 paper by Claude-Servais-Mathias Pouillet (1790-1868), who later employed this sensitive form of galvanometer to verify Ohm's law.
		On the right is a tangent galvanometer made for William Thomson (Lord Kelvin), and used by James Joule in his researches on the mechanical equivalent of heat at Glasgow.
		The tangent galvanometer at the left is in the museum in the physics department at Glasgow University in Scotland.
	physics.kenyon.edu /EarlyApparatus/Electrical_Measurements/Tangent_Galvanometer/Tangent_Galvanometer.html (1141 words)

	D'Arsonval Galvanometer
		Since the electro-magnetic torque is proportional to the current in the coil and the restoring toque is proportional to the angle of twist of the suspension fiber, at equilibrium the current through the coil is linearly proportional to its angular deflection.
		Self-contained galvanometers, such as the one by Rubicon at the right, used to be standard equipment for voltage measurements with a potentiometer.
		A 6 volt light bulb is used as a optical source, and, after a parallel beam is formed with a stop and a lens, the beam reflects from the mirror on the galvanometer movement, and, after several reflections inside to lengthen the optical lever, falls on the frosted-glass scale.
	physics.kenyon.edu /EarlyApparatus/Electrical_Measurements/DArsonval_Galvanometer/DArsonval_Galvanometer.html (678 words)

	Electrometer/Galvanometer Scale (Site not responding. Last check: 2007-11-02)
		This type of scale was used to monitor the movement of a beam of light that was reflected off the mirror of a quadrant electrometer or reflecting galvanometer.
		This was usually accomplished by measuring the time it took the reflected beam to move across a specific number of divisions on the scale.
		Until 1860 or so, the procedure was to measure the deflection of the galvanometer (quadrant electrometers had yet to be invented) by viewing the reflected image of the scale via a telescope.
	www.orau.org /ptp/collection/electrometers/scale.htm (215 words)

	Pouillet
		The sine galvanometer is similar in appearance to the tangent galvanometer, but has provision to rotate the coil about a vertical axis.
		Claude Pouillet of Paris in 1837, is a precursor of the tangent galvanometer.
		Like the tangent galvanometer, the sine galvanometer has a coil of wire carrying the current to be measured, and a magnetic compass needle in the middle of the coil.
	www.geocities.com /neveyaakov/electro_science/pouillet.html (831 words)

	The educational encyclopedia, measurements, multimeter
		Galvanometer the torque on a current loop in a uniform magnetic field is used to measure electrical magnetic field is used to measure electrical currents.
		Galvanometer the galvanometer is an electromagnetic device capable of detecting very small electrical currents.
		Galvanometers a galvanometer is an instrument for detecting small currents.
	www.educypedia.be /electronics/multimeter.htm (580 words)

	The Galvanometer as a Voltmeter and an Ammeter
		To use the galvanometer as an ammeter, a resistor is placed in parallel with the meter.
		The internal resistance computed for the galvanometer, the computed shunt resistance, and the results from comparing the measurements of the digital voltmeter and the galvanometer can be found in Table 1.
		The data from the use of the galvanometer as an ammeter is in Table 2.
	www.thought.net /jason/phy252/exp07 (568 words)

	Re: Why can't a moving coil galvanometer be highly sensitive as well as accurat
		Galvanometer is an instrument where a coil is placed in the magnetic field of a permanent magnet.
		When an electric current is passed through the coil it experiences a torque due to the interaction of the current with the magnetic field.
		That is, we are not particularly interested in knowing the amount of current through the galvanometer rather we want to measure the voltage difference across the galvanometer.
	www.madsci.org /posts/archives/aug97/868567571.Ph.r.html (350 words)

	Electric Currents and DC Circuits
		The galvanometer current Ig passing through it, is calibrated to produce a readout on a scale.
		An Ammeter is constructed using a Galvanometer in parallel to the Shunt resistor.
		A galvanometer is used to detect the current in the circuit as shown in the diagram below.
	www2.potsdam.edu /islamma/Phys305_DC_Circuits.htm (1782 words)

	Lab 4.1.2
		It consists of a coil of wire on an iron core that is pivoted on bearings between the poles of a permanent magnet.
		The scale of a galvanometer is commonly marked with intervals on both sides of a central zero.
		The galvanometer is capable of detecting currents in the micro ampere (mA) range, and the scale graduations give relative magnitudes of the current.
	www.usd.edu /phys/labs/em/4_1_2/4_1_2c.html (1190 words)

	Meters
		The meter shown in the galvanometers section has a twisted pointer although it is too small to see in the picture.
		Galvanometers are very sensitive meters which are used to measure tiny currents, usually 1mA or less.
		Analogue multimeters consist of a galvanometer with various resistors which can be switched in as multipliers (voltmeter ranges) and shunts (ammeter ranges).
	www.kpsec.freeuk.com /meters.htm (1054 words)

	Astatic Galvanometer Galileo telescope and IMSS Florance Italy
		Galileo's telescopes, and early examples of astatic galvanometers are on display at the IMSS in Florence Italy The telescope is out in front one of the first things one see's.
		Instrument such as the tangent galvanometer the galvanoscope and other simple galvanometers the needle responded to the vector sum of the horizontal component of the magnetic field of the earth and the magnetic field produced by the current being measured.
		As long as the galvanometer is being used for qualitative measurements, it is important to turn the apparatus so that the compass needle points toward magnetic north when no current is applied to the coil.
	www.scitechantiques.com /galvanometer-astatic (2812 words)

	Galvanometer Theory of Operation
		In the galvanometer, Input 1 is replaced with permanent magnets, as shown in the diagram of the G-100PD, below left.
		Note also that the drive coils of the galvanometer may be wound directly on the four poles, as in the Mueller device.
		The galvanometer coil positions as shown in the diagram at left were chosen for their ease of manufacturing.
	laser.shows.org /theoryof.htm (561 words)

	Physiology or Medicine 1924 - Presentation Speech
		To give an idea of this, some phenomena may be mentioned, which by means of the string galvanometer have been investigated by Einthoven himself: the retina current (1908, 1909), the action currents in nervus vagus (1908, 1909) and in the sympathetic chain (1923), the psychogalvanic reflex (1921), the Gaskell effect (1916), the muscular tone (1918).
		The string of the galvanometer, connected with the heart in a closed circuit in one of the usual ways, remains in the original position not only when the heart is at rest, but also when the «negativity» of the assemblage of points of the heart wall show the same value.
		A deflection is therefore in the first place to be expected at the beginning and at the end of a systole, and it presupposes that the condition of activity does not occur, respectively cease, simultaneously in all elements of the muscle.
	nobelprize.org /nobel_prizes/medicine/laureates/1924/press.html (2301 words)

	Galvanometer (Site not responding. Last check: 2007-11-02)
		This instrument is a galvanometer, a meter used for balancing or testing an external electrical circuit.
		In the days before absolute measurements were reliable the method used was to connect a known fixed resistance, a battery, and a variable resistance across the circuit to be measured, in what was known as a "bridge" configuration.
		A galvanometer, which is a centre-zero meter, often a moving coil type, was connected so that positive and negative current could be balanced out.
	www.btinternet.com /~allan.isaacs/galvanometer.html (315 words)

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