Name: hall voltage and charge carriers
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The Hall Effect

Si consideri un conduttore rettangolare che trasporta corrente con elettroni come portatori di carica. Quando un campo magnetico viene applicato perpendicolarmente al piano del conduttore, gli elettroni che si muovono in linea retta si spostano a causa della forza magnetica di deviazione.
Gli elettroni si accumulano su un lato del conduttore, lasciando cariche positive in eccesso sull'altro lato. Questa separazione di carica crea un campo elettrico all'interno del conduttore, che esercita una forza elettrica su ciascun elettrone che si oppone alla forza magnetica.
All'equilibrio, l'entità della forza elettrica bilancia la forza magnetica, fermando l'ulteriore deriva degli elettroni. La differenza di potenziale tra i due lati del conduttore è la tensione Hall.
Esprimendo la velocità di deriva in termini di corrente, la tensione Hall può essere utilizzata anche per misurare la densità numerica dei portatori di carica.
Le sonde Hall misurano l'entità di un campo magnetico sconosciuto dalla tensione Hall e dai parametri noti del conduttore.
Un'applicazione significativa di questa scoperta è che la polarità della tensione Hall implica se i portatori di carica nel conduttore sono negativi o positivi.

<ol>
	<li>OpenStax. (2019). Fisica universitaria Vol. 2. [Versione web]. Estratto da 514-516 <a href="https://openstax.org/books/university-physics-volume-2/pages/11-6-the-hall-effect">https://openstax.org/books/university-physics-volume-2/pages/11-6-the-hall-effect</a></li>
</ol>

l'effetto hall

Edwin H. Hall, nell'anno 1879, ideò un esperimento che poteva essere utilizzato per identificare la polarità dei principali portatori di carica in un materiale conduttore. Da un punto di vista storico, questo esperimento fu il primo a dimostrare che i portatori di carica nella maggior parte dei metalli sono negativi.

<img alt="Figure1" src="/files/ftp_upload/13772/13772_Figure_1.png" style="text-align: center" />

Consideriamo una lastra di metallo di larghezza L in un campo magnetico costante. Gli elettroni si muovono da destra a sinistra, quindi la forza magnetica che subiscono spinge gli elettroni verso il bordo superiore della lastra. Ciò lascia un eccesso di carica negativa sul bordo superiore della lastra e un eccesso di carica positiva sul bordo inferiore della lastra, risultando in un campo elettrico diretto dal basso verso l'alto. La concentrazione di carica su entrambi i bordi si accumula fino a quando non viene stabilita una condizione di equilibrio. All'equilibrio, la forza elettrica sugli elettroni in una direzione è bilanciata dalla forza magnetica nella direzione opposta. Questo scenario in cui i campi elettrico e magnetico sono perpendicolari l'uno all'altro è chiamato situazione a campi incrociati.

La corrente nella lastra I può essere scritta in termini della velocità di deriva vd e dell'area trasversale della lastra A. La differenza di potenziale tra i bordi della striscia, altrimenti chiamata tensione di Hall, è data da:

<img alt="Equation1" src="/files/ftp_upload/13772/13772_Equation_1.png" style="text-align: center; height: 40px;" />

La polarità della tensione di Hall mostra se i portatori di carica sono positivi o negativi. Un'altra importante applicazione di questo effetto è per materiali con una densità nota di portatori di carica. La tensione di Hall misurata può fornire il valore di un campo magnetico sconosciuto. Nei laboratori di ricerca in cui i campi degli elettromagneti utilizzati per misurazioni precise devono essere altamente stabili, una "sonda Hall" è comunemente utilizzata come parte del circuito elettronico per regolare il campo.

L'effetto Hall

Edwin H. Hall, nell'anno 1879, ideò un esperimento che poteva essere utilizzato per identificare la polarità dei portatori di carica predominanti in un conduttore ...

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hall voltage and charge carriers

Hall voltage and charge carriers are explained through Edwin H. Hall’s 1879 experiment. His setup helped identify the polarity of the main charge carriers in a conducting material. It also showed, for the first time, that the charge carriers in most metals are negative.

A metal slab is placed in a constant magnetic field. The electrons move from right to left, so the magnetic force pushes them toward the top edge of the slab. This leaves excess negative charge at the top and excess positive charge at the bottom. As a result, an electric field forms from the bottom edge to the top edge.

The charge buildup continues until equilibrium is reached. At that point, the electric force on the electrons balances the magnetic force in the opposite direction. This is called a crossed-field situation because the electric and magnetic fields are perpendicular to each other. The current in the slab, I, can be written in terms of the drift velocity, v d, and the cross-sectional area, A.

The potential difference between the two edges is called the Hall voltage. Its polarity reveals whether the charge carriers are positive or negative. When the density of charge carriers is known, the Hall voltage can also be used to find an unknown magnetic field. In research labs, a Hall probe is often used in electronic circuits to help regulate electromagnet fields so they stay steady for precise measurements.

Hall Voltage and Charge Carriers

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the hall effect

Hall voltage and charge carriers are explained through Edwin H. Hall’s 1879 experiment. His setup helped identify the polarity of the main charge carriers in a conducting material. It also showed, for the first time, that the charge carriers in most metals are negative. A metal slab is placed in a constant magnetic field. The electrons move from right to left, so the magnetic force pushes them toward the top edge of the slab. This leaves excess negative charge at the top and excess positive...

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Learn how Hall voltage forms in a magnetic field, how it reveals charge carrier polarity, and how Hall probes help measure and control magnetic fields.

Hall Voltage and Charge Carriers | JoVE K12

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Hall Voltage and Charge Carriers

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