Hall effect diagram, showing electron flow (rather than conventional current). Legend: 1. Electrons (not conventional current!) 2. Hall element, or Hall sensor 3. Magnets 4. Magnetic field 5. Power source Description: In drawing "A", the Hall element takes on a negative charge at the top edge (symbolised by the blue color) and positive at the lower edge (red color). In "B" and "C", either the electric current or the magnetic field is reversed, causing the polarization to reverse. Reversing both current and magnetic field (drawing "D") causes the Hall element to again assume a negative charge at the upper edge. The Hall effect refers to the potential difference (Hall voltage) on the opposite sides of an electrical conductor through which an electric current is flowing, created by a magnetic field applied perpendicular to the current. Edwin Hall discovered this effect in 1879. Image File history File links Drawn by User:IMeowbot Hall effect demo. ...
Image File history File links Drawn by User:IMeowbot Hall effect demo. ...
In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ...
Electric current is the flow (movement) of electric charge. ...
Potential difference is a quantity in physics related to the amount of energy that would be required to move an object from one place to another against various types of force. ...
In science and engineering, conductors, such as a electrical connector, are materials that readily conduct electric current through electrical conduction. ...
In electricity, current refers to electric current, which is the flow of electric charge. ...
Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ...
Fig. ...
See Edwin Arthur Hall for the former U.S. Congressman from New York and Edwin R. Hall for the Kansas man accused of murdering Kelsey Smith Edwin Herbert Hall (November 7, 1855 - November 20, 1938) was an American physicist who discovered the Hall effect. Hall conducted thermoelectric research at Harvard...
1879 (MDCCCLXXIX) was a common year starting on Wednesday (see link for calendar). ...
The ratio of the voltage created to the product of the amount of current and the magnetic field divided by the element thickness is known as the Hall coefficient. It is a characteristic of the material from which the conductor is made, as its value depends on the type, number and properties of the charge carriers that constitute the current. In mathematics, a coefficient is a constant multiplicative factor of a certain object. ...
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ...
Explanation
The Hall effect comes about due to the nature of the current flow in a conductor. Current consists of the movement of many small charge-carrying "particles" (typically, but not always, electrons). These charges experience a force, called the Lorentz Force, when a magnetic field is present that is not parallel to their motion. When such a magnetic field is absent, the charges follow an approximately straight, 'line of sight' path. However, when a perpendicular magnetic field is applied, their path is curved so that moving charges accumulate on one face of the material. This leaves equal and opposite charges exposed on the other face, where there is a dearth of mobile charges. The result is an asymmetric distribution of charge density across the hall element that is perpendicular to both the 'line of sight' path and the applied magnetic field. The separation of charge establishes an electric field that opposes the migration of further charge, so a steady electrical potential builds up for as long as the current is flowing. e- redirects here. ...
Lorentz force. ...
Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ...
In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ...
Electrical potential is the potential energy per unit charge associated with a static (time-invariant) electric field, also called the electrostatic potential or the electric potential, typically measured in volts. ...
For a simple metal where there is only one type of charge carrier (electrons) the Hall voltage VH is given by Image File history File links Drawn by User:IMeowbot Hall effect demo. ...
Charge carrier denotes in physics a free (mobile, unbound) particle carrying an electric charge. ...
The Hall coefficient is defined as
where I is the current across the plate length, B is the magnetic flux density, d is the depth of the plate, e is the electron charge, and n is the bulk density of the carrier electrons. Bulk density a property of particulate materials. ...
As a result, the Hall effect is very useful as a means to measure both the carrier density and the magnetic field.
One very important feature of the Hall effect is that it differentiates between positive charges moving in one direction and negative charges moving in the opposite. The Hall effect offered the first real proof that electric currents in metals are carried by moving electrons, not by protons. 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. A semiconductor is a material that is an insulator at very low temperature, but which has a sizable electrical conductivity at room temperature. ...
For the following two reasons the electron hole was introduced into calculations: If an electron is excited into higher state it leaves a hole in its old state. ...
Hall effect in Semiconductors The simple formula for the Hall coefficient given above becomes more complex in semiconductors where the carriers are generally both electrons and holes which may be present in different concentrations and have different mobilities. For moderate magnetic fields the Hall coefficient is Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ...
Holes can refer to: The book by Louis Sachar, Holes (novel) The 2003 Disney film based on the book, Holes (film) See also: Hole Category: ...
This does not adequately cite its references or sources. ...
where is the electron concentration, the hole concentration, the electron mobility , the hole mobility and the electronic charge.
For large applied fields the simpler expression analagous to that for a single carrier type holds.
Technological applications So-called "Hall effect sensors" are readily available from a number of different manufacturers, and may be used in various sensors such as fluid flow sensors, power sensors, and pressure sensors. The magnetic piston (1) in this pneumatic cylinder will cause the Hall effect sensors (2 and 3) mounted on its outer wall to activate when it is fully retracted or extended. ...
A flow sensor is a device for sensing the rate of fluid flow. ...
Digital air pressure sensor A pressure sensor measures the pressure, typically of gases or fluids. ...
Quantum Hall effect For a two dimensional electron system which can be produced in a mosfet transistor. In the presence of large magnetic field strength and low temperature, one can observe the quantum Hall effect, which is the quantization of the Hall voltage. The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is by far the most common field-effect transistor in both digital and analog circuits. ...
Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ...
This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ...
The quantum Hall effect is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall conductance takes on the quantized values where is the elementary charge and is Plancks constant. ...
Fig. ...
Hall effect in magnetic systems In ferromagnetic materials (and paramagnetic materials in a magnetic field), the Hall resistivity includes an additional contribution, known as the Anomalous Hall Effect (or the Extraordinary Hall effect), which depends directly on the magnetization of the material, and is often much larger than the ordinary Hall effect. (Note that this effect is not due to the contribution of the magnetization to the total magnetic field.) Although a well-recognized phenomenon, there is still debate about its origins in the various materials. The anomalous Hall effect can be either an extrinsic (disorder-related) effect due to spin-dependent scattering of the charge carriers, or an intrinsic effect which can be described in terms of the Berry phase effect in the crystal momentum space (k-space). Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...
Paramagnetism is the tendency of the atomic magnetic dipoles, due to quantum-mechanical spin, in a material that is otherwise non-magnetic to align with an external magnetic field. ...
Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ...
Magnetization is a property of some materials (e. ...
Magnetization is a property of some materials (e. ...
Magnetic field lines shown by iron filings In physics, a magnetic field is a solenoidal vector field in the space surrounding moving electric charges, such as those in electric currents and bar magnets. ...
In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ...
Scattering is a general physical process whereby some forms of radiation, such as light, sound or moving particles, for example, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which it passes. ...
Charge carrier denotes in physics a free (mobile, unbound) particle carrying an electric charge. ...
In quantum mechanics, the Berry phase is a phase acquired by quantum states when subjected to adiabatic processes, resulting from the geometrical properties of the parameter space of the Hamiltonian. ...
Applications Hall effect devices produce a very low signal level and thus require amplification. While suitable for laboratory instruments, the vacuum tube amplifiers available in the first half of the 20th century were too expensive, power consuming, and unreliable for everyday applications. It was only with the development of the low cost integrated circuit that the Hall effect sensor became suitable for mass application. Many devices now sold as "Hall effect sensors" are in fact a device containing both the sensor described above and a high gain integrated circuit (IC) amplifier in a single package. Recent advances have resulted in the addition of ADC (Analog to Digital) converters and I²C (Inter-integrated circuit communication protocol) IC for direct connection to a microcontroller's I/O port being integrated into a single package, see Advanced Hall Effect Current Transducer. Reed switch electrical motors using the hall effect IC is another application. Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ...
Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ...
(19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999...
Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ...
The magnetic piston (1) in this pneumatic cylinder will cause the Hall effect sensors (2 and 3) mounted on its outer wall to activate when it is fully retracted or extended. ...
Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ...
I²C is a multi-master serial computer bus invented by Philips that is used to attach low-speed peripherals to a motherboard, embedded system, or cellphone. ...
It has been suggested that Reed relay be merged into this article or section. ...
Hall probes are often used to measure magnetic fields, or inspect materials (such as tubing or pipelines) using the principles of Magnetic flux leakage. Magnetic flux leakage (MFL) is a magnetic method of nondestructive testing that is used to detect corrosion and pitting in steel structures, most commonly pipelines and storage tanks. ...
Advantages over other methods Hall effect devices when appropriately packaged are immune to dust, dirt, mud, and water. These characteristics make Hall effect devices better for position sensing than alternative means such as optical and electromechanical sensing.
Hall effect current sensor with internal integrated circuit amplifier. 8 mm opening. Zero current output voltage is midway between the supply voltages that maintain a 4 to 8 volt differential. Non-zero current response is proportional to the voltage supplied and is linear to 60 amperes for this particular (25 A) device. When electrons flow through a conductor, a magnetic field is produced. Thus, it is possible to create a non-contacting current sensor. The device has three terminals. A sensor voltage is applied across two terminals and the third provides a voltage proportional to the current being sensed. This has several advantages; no additional resistance (a shunt, required for the most common current sensing method) need be inserted in the primary circuit. Also, the voltage present on the line to be sensed is not transmitted to the sensor, which enhances the safety of measuring equipment. Image File history File links Hall effect DC current sense 25 Ampere. ...
Image File history File links Hall effect DC current sense 25 Ampere. ...
In electricity, a shunt is a device which allows electrical current to pass around another point in the circuit. ...
Ferrite toroid Hall effect current transducer
Diagram of Hall effect current transducer integrated into ferrite ring. Hall sensors can detect stray magnetic fields easily, including that of Earth, so they work well as electronic compasses: but this also means that such stray fields can hinder accurate measurements of small magnetic fields. To solve this problem, Hall sensors are often integrated with magnetic shielding of some kind. For example, a Hall sensor integrated into a ferrite ring (as shown) can reduce stray fields by a factor of 100 or better. This configuration also provides an improvement in signal-to-noise ratio and drift effects of over 20 times that of a 'bare' Hall device. The range of a given feedthrough sensor may be extended upward and downward by appropriate wiring. To extend the range to lower currents, multiple turns of the current-carrying wire may be made through the opening. To extend the range to higher currents, a current divider may be used. The divider splits the current across two wires of differing widths and the thinner wire, carrying a smaller proportion of the total current, passes through the sensor. Image File history File links RAZC-GENARRv1. ...
Image File history File links RAZC-GENARRv1. ...
Multiple 'turns' and corresponding transfer function. The principle of increasing the number of 'turns' a conductor takes around the ferrite core is well understood, each turn having the effect of 'amplifying' the current under measurement. Often these additional turns are carried out by a staple on the PCB. Image File history File links Download high-resolution version (2200x2800, 311 KB)[edit] Summary The principle of increasing the number of turns a conductor takes around the ferrite core is explained in this diagram. ...
Image File history File links Download high-resolution version (2200x2800, 311 KB)[edit] Summary The principle of increasing the number of turns a conductor takes around the ferrite core is explained in this diagram. ...
Split ring clamp-on sensor A variation on the ring sensor uses a split sensor which is clamped onto the line enabling the device to be used in temporary test equipment. If used in a permanent installation, a split sensor allows the electrical current to be tested without dismantling the existing circuit.
Analogue multiplication The output is proportional to both the applied magnetic field and the applied sensor voltage. If the magnetic field is applied by a solenoid, the sensor output is proportional to product of the current through the solenoid and the sensor voltage. As most applications requiring computation are now performed by small (even tiny) digital computers, the remaining useful application is in power sensing, which combines current sensing with voltage sensing in a single Hall effect device. ...
Power sensing By sensing the current provided to a load and using the device's applied voltage as a sensor voltage it is possible to determine the power dissipated by a device. This power is (for direct current devices) the product of the current and the voltage. With appropriate refinement the devices may be applied to alternating current applications where they are capable of reading the true power produced or consumed by a device. Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
City lights viewed in a motion blurred exposure. ...
Position and motion sensing Hall effect devices used in motion sensing and motion limit switches can offer enhanced reliability in extreme environments. As there are no moving parts involved within the sensor or magnet, typical life expectancy is improved compared to traditional electromechanical switches. Additionally, the sensor and magnet may be encapsulated in an appropriate protective material.
Automotive ignition and fuel injection If the magnetic field is provided by a rotating magnet resembling a toothed gear, an output pulse will be generated each time a tooth passes the sensor. This is used in modern automotive primary distributor ignition systems, replacing the earlier contact breaker ('points', which were prone to wear and required periodic adjustment and replacement). Similar sensor signals are used to control multi-port sequential fuel injection systems, where each cylinder's intake runner is fed fuel from an injector consisting of a spray valve regulated by a solenoid. The sequences are timed to match the intake valve openings and the duration of each sequence by the Engine Control Unit (computer). Karl Benzs Velo model (1894) - entered into the first automobile race An automobile or motor car (usually shortened to just car) is a wheeled passenger vehicle that carries its own motor. ...
Distributor cap. ...
The ignition system of an internal-combustion engine is an important part of the overall engine system that provides for the timely burning of the fuel mixture within the engine. ...
Breaker arm with contact points at the left. ...
// Fuel injection is a means of metering fuel into an internal combustion engine. ...
An Engine Control Unit (ECU) also known as an Engine Control Module (ECM) or Powertrain Control Unit/Module (PCU, PCM) if it controls both an engine and a transmission, is an electronic control unit which controls various aspects of an internal combustion engines operation. ...
Wheel rotation sensing The sensing of wheel rotation is especially useful in anti-lock brake systems. The principles of such systems have been extended and refined to offer more than anti-skid functions, now providing extended vehicle "handling" enhancements. An anti-lock braking system (commonly known as ABS, from the German name Antiblockiersystem given to it by its inventors at Bosch) is a system on motor vehicles which prevents the wheels from locking while braking. ...
Solar Car energy management Accurate and efficient management of all aspects of energy is a critical aspect of any successful solar car - Hall effect current transducers are an ideal solution due to their high accuracy, environmental hardiness and low power consumption.
Electric motor control Some types of brushless DC electric motors use Hall effect sensors to detect the position of the rotor and feed that information to the motor controller. A brushless DC motor (BLDC) is an AC synchronous electric motor that from a modeling perspective looks very similar to a DC motor. ...
Industrial Applications Applications for Hall Effect sensing have also expanded to the industrial/off-highway market, which now use Hall Effect Joysticks to control hydraulic valves, replacing the traditional mechanical levers. Such applications include; Mining Trucks, Backhoe Loaders, Cranes, Diggers, Scissor Lifts, etc. A leading manufacturer of Industrial Hall Effect Joysticks is P-Q Controls, Inc., which was one of the first companies to expand the use of Hall Effect sensing to such applications in the 1980's, and in fact holds exclusive patents for contactless sensing.
The Corbino effect The Corbino effect is a phenomenon similar to the Hall effect, but a disk-shaped metal sample is used in place of a rectangular one. A radial current through a circular disc subjected to a magnetic field perpendicular to the plane of the disk, produces a "circular" current through the disk. Orso Mario Corbino (30 April 1876, Augusta – 23 January 1937, Rome) was an Italian physicist and politician. ...
See also Image File history File links Nuvola_apps_ksim. ...
Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ...
An eddy current is a phenomenon caused by a moving magnetic field intersecting a conductor or vice-versa. ...
The elementary charge (symbol e or sometimes q) is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron. ...
2 kW Laboratory Hall Thruster in operation at the Princeton Plasma Physics Laboratory A Hall effect thruster is a type of ion thruster in which the propellant is accelerated by an electric field in a plasma discharge with a radial magnetic field. ...
Hall Probes Hall probes are used to measure magnetic field strength. ...
The Nernst Effect is a phenomenon observed when a magnetic field is applied across a flow of heat energy, an electric field will be induced at right angles to the magnetic field. ...
Nernst-Ettingshausen effect is produced when an electric current flows across the lines of force of a magnetic field, an electromotive force is observed which is at right angles to both the primary current and the magnetic field. ...
The quantum Hall effect is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall conductance takes on the quantized values where is the elementary charge and is Plancks constant. ...
The Thermal hall effect is the thermal analog of the Hall effect for conductors. ...
A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
External links and references - Patents
- U.S. Patent 1,778,796 , P. H. Craig, System and apparatus employing the Hall effect
- General
- Science World (wolfram.com) article.
- "The Hall Effect". nist.gov.
- Hall, Edwin, "On a New Action of the Magnet on Electric Currents". American Journal of Mathematics vol 2 1879.
- Spin Hall Effect Detected at Room Temperature
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