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The Hall effect is a potential difference (voltage) on opposite sides of a thin sheet of conducting or semiconducting material in the form of a 'Hall bar' or a van der Pauw element through which an electric current is flowing, created by a magnetic field applied perpendicular to the Hall element. The ratio of the voltage created to the amount of current is known as the Hall resistance, and is a characteristic of the material in the element. Dr. Edwin Hall discovered this effect in 1879.1 Analysis
The Hall effect comes about due to the nature of the current flow in the conductor. Current consists of many small charge-carrying "particles" (typically electrons) which see a force due to the magnetic field. Some of these charge elements end up forced to the sides of the conductors, where they create a pool of net charge. This is only notable in larger conductors where the separation between the two sides is large enough.
One 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. 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.
By measuring the Hall voltage across the element, one can determine the strength of the magnetic field applied. So called Hall effect sensors are readily available from a number of different manufacturers. 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. These Hall effect switches generally consist of a Hall effect sensor, one or more logic gates and a transistor used to switch the electric current on or off.
Alternately, by applying a known magnetic field (typically from a permanent magnetThis article is about magnetized material. Magnet is also the name of a commune in the Allier departement, in France A magnet is an object that has a magnetic field. A so-called permanent magnet is made of a ferromagnetic material. Such materials consist) one can use the Hall voltage to instead measure the current through the element. This can be particularly useful as it allows one to measure the current in a conductor remotely through inductionElectromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic field. Michael Faraday was the first to describe this phenomenon mathematically: he found that the electromot. This is widely used commercially in "live wire detectors", which allow you to quickly identify which wires are carrying current without plugging into them.
In the presence of large magnetic field strength and low temperatureTemperature is the physical property of a system which underlies the common notions of "hot" and "cold"; the material with the higher temperature is said to be hotter. General description The formal properties of temperature are studied in thermodynamics., one can observe the quantum Hall effectThe quantum Hall effect is a quantum mechanical version of the Hall effect, observed in two-dimensional systems of electrons subjected to low temperatures and strong magnetic fields, in which the Hall conductance sigma takes on the quantized values : wher, which is the quantizationwavefunctions of an electron in a hydrogen atom possessing definite energy (increasing downward: n 1,2,3,. and angular momentum (increasing across: s p d . Brighter areas correspond to higher probability density for a position measurement. The angular mom of the Hall resistance.
In ferromagnetic materials, the Hall resistivity also shows an anomalous contribution, known as the Anomalous Hall Effect, proportional to the magnetization of the material. Although a well-recognised phenomena, there is still debate about its origins.
