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Topic: Hall effect

	Hall Effect
		The transverse voltage (Hall effect) measured in a Hall probe has its origin in the magnetic force on a moving charge carrier.
		The Hall effect is a conduction phenomenon which is different for different charge carriers.
		The Hall effect can be used to measure the average drift velocity of the charge carriers by mechanically moving the Hall probe at different speeds until the Hall voltage disappears, showing that the charge carriers are now not moving with respect to the magnetic field.
	hyperphysics.phy-astr.gsu.edu /hbase/magnetic/hall.html (380 words)

	Hall (Site not responding. Last check: 2007-11-05)
		Hall was pursuing the question first posed by Maxwell as to whether the resistance of a coil excited by a current was affected by the presence of a magnet.
		This effect is observed as a voltage (Hall voltage) perpendicular to the direction of current in the conductor.
		In particular, the positive Hall coefficients exhibited by metals such as magnesium and aluminium are a clear indication that a naive picture of a sea of conduction electrons is inappropriate because the majority carriers are clearly positively charged (and are, in fact, holes).
	chem.ch.huji.ac.il /~eugeniik/history/hall.html (793 words)

	THE HALL EFFECT (Site not responding. Last check: 2007-11-05)
		Hall Mobility is an expression of the extent to which the Hall effect takes place in a semiconductor material.
		A Hall generator is a device that makes use of the Hall effect for the purpose of generating a direct current voltage in the presence of a magnetic field.
		B is the magnetic field, and RH is the proportionality constant known as the Hall constant or Hall coefficient.
	www.math.sunyit.edu /projects/vector/hall.html (1648 words)

	Wikinfo \| Hall effect
		The Hall effect (discovered by Dr. Edwin Hall in 1879) is a potential difference (voltage) on opposite sides of a thin sheet of conducting or semiconducting material (the Hall element) through which an electric current is flowing, created by a magnetic field applied perpendicular to the Hall element.
		Interestingly enough, the Hall effect also showed that in some substances (especially semiconductors), it is more appropriate to think of the current as positive "holes" moving rather than negative electrons.
		The most common types are analog (or Linear) Hall effect sensors, which output a voltage that is proportional to the applied magnetic field, and digital Hall effect sensors, which are often used as magnetically controlled switches -- they turn on or off when the applied magnetic field reaches a certain level.
	www.wikinfo.org /wiki.php?title=Hall_effect (508 words)

	The Hall Effect
		The situation for the Hall effect is illustrated in Fig.
		The Hall bar sample itself is attached to the underside of an integrated circuit “chip carrier;” electrical leads attached to the Hall bar, as discussed with Fig.
		Connections for the Hall bar sample, the junction box, and the equipment used in the Hall effect measurement are illustrated in Fig.
	class.phys.psu.edu /p457/experiments/html/hall_effect_2004.htm (2083 words)

	Bell Labs: The Fractional Quantum Hall Effect (Site not responding. Last check: 2007-11-05)
		In 1879, Edwin Hall, a graduate student at Johns Hopkins University, discovered that, when a magnetic field was applied perpendicularly to a thin metal sheet that was conducting current, a small electrical voltage appeared that was perpendicular to both the sheet and the magnetic field.
		The Hall voltage and Hall resistance (the ratio of the Hall voltage to the current) are now commonly used in physics laboratories to measure the strengths of magnetic fields, as well as charge densities in various metals.
		This "anomalous" effect took the physics community by surprise and came to be known as the fractional quantum Hall effect.
	www.bell-labs.com /news/1998/october/13/2.html (719 words)

	Palmer Craig: Hall Effect Device (Battery, rectifier, amplifier) (Site not responding. Last check: 2007-11-05)
		As the effect of the magnetic field is small in all cases, a great refinement of the potentiometer and measuring circuits is imperative with weak fields, and the preparation of the bismuth strips presents great difficulties and requires special methods.
		Where R is the Hall coefficient, d the thickness of the film in centimeters, i the longitudinal current in abamperes, H the magnetic field strength in gausses, and E the net Hall emf.
		The "Corbino" effect is similar to the "Hall" effect, wherein a radial current through a circular disc subjected to a magnetic field perpendicular to the plane of the disc, produces a "circular" current through the disc.
	www.rexresearch.com /craig/craig.htm (4614 words)

	The Hall Effect
		The remaining articles in the top 20 ranking cover the spectrum of Hall effect phenomena that have been discovered since the early 1970s and are now being studied in a host of materials from atypical ferromagnets to high-tc and unconventional superconductors.
		These include the giant Hall effect, the integer and fractional quantum Hall effects, the anomalous Hall effect, theoretical studies of the spin Hall effect (in which spin-up and spin-down electrons accumulate on opposite sides of a sample), and the intrinsic spin Hall effect.
		Since the spin Hall effect itself was demonstrated experimentally in 2004, the two-year list of highly cited articles in Hall effect research is dominated by experimental and theoretical analyses of this phenomenon.
	www.esi-topics.com /hall/index.html (514 words)

	Hall effect - SensorWiki
		The hall voltage is directly proportional to the strength of the magnetic field.
		Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal combustion engine ignition timing or tachometers.
		Hall, Edwin, "On a New Action of the Magnet on Electric Currents (http://www.stenomuseet.dk/skoletj/elmag/kilde9.html)".
	www.sensorwiki.org /index.php/Hall_effect (695 words)

	How It Works: Hall Effect Motor
		For many years the Hall effect was not used in practical applications because the generated voltage in the gold film was extremely low.
		This Hall effect IC has a built in voltage regulator and may work in the range from 4.5 to 24V.
		The magnetic field of the additional magnet placed near the Hall effect IC interacts with the magnetic field of the magnets on the rotor.
	www.simplemotor.com /hemotor.htm (746 words)

	The Hall-Effect Sensor (Site not responding. Last check: 2007-11-05)
		Some Hall Sensors use a moving magnet attached to a timing chain sprocket (GM) or notches in the flex plate (Chrysler) to generate a signal.
		Chrysler began using Hall Sensors with the introduction of the Omni/Horizon 1.7L engine back in 1978 and continued using it in later models.
		These Hall Sensors work from an 8 volt power supply and the output is a 5 volt-0 volt signal to the Engine Controller (EC).
	www.kemparts.com /TechTalk/tt10.asp (719 words)

	Hall-Effect Sensors: Theory and Application
		Hall effect sensors, based on a magnetic phenomena, are one of the most commonly used sensing technologies today.
		In the 1970s it became possible to build Hall effect sensors on integrated circuits with onboard signal processing circuitry, vastly reducing the cost and enabling widespread practical use.
		Most of the technical information on Hall effect sensors is supplied by sensor manufacturers and is slanted toward a particular product line.
	www.sensorsportal.com /HTML/BOOKSTORE/Hall_Effect_Sensors.htm (406 words)

	Hall Effect
		To demonstrate the temperature dependence of electrical conductivity and the Hall Effect in semi-conductors.
		Voltmeter for measuring the Hall Voltage 30 to 100 mV.
		Measure and record the the Hall voltage for Magnet coil currents of 4, 5, 6, 7, and 8 Amperes.
	www.phy.davidson.edu /ModernPhysicsLabs/halleffect.htm (1262 words)

	II. The Hall Effect
		The basic physical principle underlying the Hall effect is the Lorentz force.
		The objective of the Hall measurement in the van der Pauw technique is to determine the sheet carrier density n
		The Hall voltage measurement consists of a series of voltage measurements with a constant current I and a constant magnetic field B applied perpendicular to the plane of the sample.
	www.eeel.nist.gov /812/effe.htm (938 words)

	The Hall Effect (Site not responding. Last check: 2007-11-05)
		He was actually using the Hall effect to characterize the transistor in a high magnetic field at very low temperature.
		As he increased the magnetic field, instead of seeing the gradual build up of the Hall effect, he saw it jump up in little steps, reaching one plateau and then suddenly popping up to a higher one.
		The quantum Hall effect is now used to generate the standard of electrical resistance which is needed to calibrate sensitive electronic test equipment.
	www.rialian.com /rnboyd/hall.htm (391 words)

	Hall Effect -- from Eric Weisstein's World of Physics
		Therefore, if sensing electrodes are placed across the transverse dimension of the plate, a voltage, called the Hall voltage, will appear.
		From these considerations, we see that a Hall sensor or sample in a Hall measurement should have low carrier density, but the carriers should have high mobility.
		is actually the Hall mobility, so measuring the Hall voltage is a way of measuring mobility in a material.
	scienceworld.wolfram.com /physics/HallEffect.html (284 words)

	2.1.3 The Hall Effect
		effect as an important observation in materials science and at the same time another irrefutable proof that classical physics just can't hack it when it comes to electrons in crystals.
		The Hall effect describes what happens to current flowing through a conducting material - a metal, a semiconductor - if it is exposed to a magnetic field B.
		or the carrier concentation, the Hall effect cna be used to measure magnetic field strengths B (not so easily done otherwise!).
	www.tf.uni-kiel.de /matwis/amat/mw2_ge/kap_2/backbone/r2_1_3.html (949 words)

	Hall effect - Wikipedia, the free encyclopedia
		Hall probes are used to measure magnetic fields, and make use of the Hall effect.
		Hall sensors can easily detect stray magnetic fields, including that of Earth, so they work well as electronic compasses.
		For example, a Hall sensor integrated into a ferrite ring (as shown) can reduce stray fields by a factor of 100 or better.
	en.wikipedia.org /wiki/Hall_effect (1667 words)

	Hall Effect - Magnetoresistive Sensors (Site not responding. Last check: 2007-11-05)
		Hall Effect Quiz, with diagrams of the magnetic field
		Hall Effect Current Sensors Hall Sensors A Tutorial on Hall Sensors A Tutorial on the New Magnetoresistive Technology Current Sensor F.W. Bell Hall Sensor Spice Models F. Bell seems to be the only company to offer Spice Models for their sensors.
		Hall Effect switches are bounce free by nature making them suitable for use in keyboards.
	archive.chipcenter.com /circuitcellar/july99/c79r2.htm (472 words)

	Introduction to the Quantum Hall Effect (Site not responding. Last check: 2007-11-05)
		The discovery of Quantum Hall Effect(QHE) is a remarkable achievement in condensed matter physics.
		At low temperatures and in strong magnetic fields, it is found that the Hall resistance of a two dimensional electron system has plateaus as a function of the number of electrons.
		Due to the high precision of the measurement, the quantization of the Hall resistance is now used as the standard of resistance.
	www.pha.jhu.edu /~qiuym/qhe/qhe.html (129 words)

	Physics News Update 693
		Physicists in Japan have theoretically shown that an optical equivalent of the Hall effect exists, and that this hypothesis could be borne out with experiments with polarized light.
		In the classic Hall effect, an electric current, pulled along a conductor by an electric field, will be deflected sideways somewhat if in addition a magnetic field (perpendicular to the electric field and to the plane of the conductor) is applied.
		In effect, they are predicting a correction to Snell's law for spin-polarized light.
	www.aip.org /pnu/2004/split/693-1.html (224 words)

	Boris Skoric: Quantum Hall Effect
		Since the Hall voltage is proportional to the current and the field strength, sending a known current through a medium and measuring the Hall voltage tells you the field strength.
		The Hall conductance is a non-equilibrium property (electrons are injected into an edge channel and don't get time to equilibrate with the localised bulk states), while by tunneling one probes the equilibrium energy eigenstates.
		Another effect of the interactions turns out to be that the so-called "neutral modes", which are degrees of freedom that are not related to the charge of the electrons, get strongly suppressed.
	members.home.nl /skoric/quantum (3046 words)

	Quantum Hall Effect
		The previous Nobel prize awarded in the area of semiconductor physics was to Bardeen, Shockley and Brattain for invention of the transistor.
		In a two-dimensional metal or semiconductor the Hall effect is also observed, but at low temperatures a series of steps appear in the Hall resistance as a function of magnetic field instead of the monotonic increase.
		The difference in the QHE is that the Hall resistance can not change from the quantised value for the whole time the Fermi energy is in a gap, i.e between the fields (a) and (b) in the diagram, and so a plateau results.
	www.warwick.ac.uk /~phsbm/qhe.htm (1086 words)

	Fractional Quantum Hall Effect
		In high mobility semiconductor heterojunctions the integer quantum Hall effect (IQHE) plateaux are much narrower than for lower mobility samples.
		This is the fractional quantum Hall effect (FQHE) whose discovery in 1982 was completely unexpected.
		While in the integer effect gaps are due to magnetic quantisation of the single particle motion, in the fractional effect the gaps arise from collective motion of all the electrons in the system.
	www.warwick.ac.uk /~phsbm/fqhe.htm (687 words)

	Hall-Effect Sensors
		The active sensing area of the sensor is 100 X 100 um.
		This allows one to make hall effect measurements in areas not previously accessible due to the size of commonly available packaged sensors.
		High linearity of the hall voltage versus magnetic field and small temperature dependence of sensitivity sets this sensor apart from commonly available hall effect sensors.
	www.cryomagnetics.com /hall-sensor.htm (186 words)

	Direct electronic measurement of the spin Hall effect: Nature
		Consistent with this effect, electrically induced spin polarization was recently detected by optical techniques at the edges of a semiconductor channel
		Here we report electrical measurements of the spin Hall effect in a diffusive metallic conductor, using a ferromagnetic electrode in combination with a tunnel barrier to inject a spin-polarized current.
		Such a voltage is proportional to the component of the injected spins that is perpendicular to the plane defined by the spin current direction and the voltage probes.
	www.nature.com /nature/journal/v442/n7099/abs/nature04937.html (328 words)

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