Name: electrical current and electron drift
Uploaded: 2023-04-30T12:38:36.000Z
Duration: 1 min 19 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Physical Science

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Motion and Stability- Forces and Interactions

PS.PSc.6.2

Drift Velocity

Los electrones libres en un conductor viajan en trayectorias aleatorias y chocan con otros electrones y partículas.
En un campo eléctrico, los electrones que se mueven aleatoriamente se desplazan gradualmente en la dirección opuesta al campo eléctrico aplicado.
Por lo tanto, la velocidad promedio de las partículas cargadas libremente en un material debido a un campo eléctrico se conoce como velocidad de deriva. Es la relación entre la corriente en un conductor y el producto de la concentración de partículas cargadas, la magnitud de la carga de cada partícula y el área de la sección transversal del conductor. La unidad SI de velocidad de deriva es metros por segundo.
Considere un alambre de cobre con un diámetro de 1 mm. ¿Cuál sería la velocidad media de deriva de los electrones en el cable cuando una corriente de 10 A lo atraviesa?
Para comenzar, calcule la densidad de electrones libres en el cable de cobre. El número de electrones libres en el cobre es igual al número de átomos de cobre por metro cúbico. En segundo lugar, calcule el área de la sección transversal del cable.
Al reorganizar y sustituir los términos, se puede determinar la velocidad de deriva. El signo negativo indica que las cargas se mueven en la dirección opuesta a la corriente convencional.

<ol>
	<li>OpenStax. (2019). Física Universitaria Vol. 2. [Versión web], págs. 95-96. Obtenido de <a href="https://openstax.org/books/university-physics-volume-2/pages/9-1-electrical-current">https://openstax.org/books/university-physics-volume-2/pages/9-1-electrical-current</a></li>
</ol>

velocidad de deriva

La alta velocidad de las señales eléctricas se debe al hecho de que la fuerza entre cargas actúa rápidamente a distancia. Así, cuando una carga libre es forzada dentro de un cable, la carga entrante empuja a otras cargas hacia adelante debido a la fuerza repulsiva entre cargas del mismo tipo. Estas cargas en movimiento mueven a las cargas más lejos a lo largo de la línea. La densidad de carga en un sistema no se puede incrementar fácilmente, por lo que la señal se transmite rápidamente. La onda de choque eléctrica resultante se mueve a través del sistema a casi la velocidad de la luz. Para ser precisos, esta señal en rápido movimiento, u onda de choque, es un cambio propagado rápidamente en el campo eléctrico. Los buenos conductores tienen grandes magnitudes de cargas libres. En los metales, las cargas libres son electrones libres. La distancia que un electrón individual puede moverse entre colisiones con átomos u otros electrones es bastante pequeña. Las trayectorias de los electrones parecen, por lo tanto, casi aleatorias, como el movimiento de los átomos en un gas. Pero hay un campo eléctrico en el conductor que hace que los electrones se desplacen en la dirección opuesta (opuesta al campo, ya que están cargados negativamente). La velocidad promedio de las cargas libres se conoce como velocidad de deriva y se representa en metros por segundo. La velocidad de deriva es bastante pequeña, del orden de 10-4 m/s, ya que hay muchas cargas libres. Las colisiones de los electrones libres transfieren energía a los átomos del conductor. El campo eléctrico realiza trabajo al mover a los electrones a lo largo de una distancia, pero ese trabajo no aumenta la energía cinética de los electrones. Las cargas de las partículas en movimiento pueden ser positivas o negativas dependiendo del tipo de material. En los metales, las cargas en movimiento son negativas (electrones), mientras que en un gas ionizado (plasma), las cargas en movimiento pueden incluir tanto electrones como iones cargados positivamente. En el caso de un semiconductor como el silicio, la conducción es parcialmente por electrones y huecos. Los huecos son sitios vacantes de electrones faltantes, que actúan como cargas positivas. La corriente convencional se trata como un flujo de cargas positivas, independientemente de si las cargas libres en el conductor son positivas, negativas o ambas; mientras que en un conductor metálico, las cargas en movimiento son electrones, pero la corriente todavía apunta en la dirección en la que fluirían las cargas positivas.

Velocidad de Deriva

La alta velocidad de las señales eléctricas se debe al hecho de que la fuerza entre las cargas actúa rápidamente a distancia. Así, cuando se obliga a una carga gratuita ...

Education

Educación

JoVE Core

Physics

Física

Unit 1

Unidad 1

Current and Resistance

Corriente y resistencia

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

electrical current and electron drift

Electrical current in a conductor depends on moving charges and the tiny drift speed of those charges. When a free charge enters a wire, it pushes nearby charges ahead because like charges repel each other. That push spreads through the material very quickly, so the electrical signal moves through the system at nearly the speed of light.

This fast signal is not the same as the slow motion of each charge. It is a rapidly spreading change in the electric field, often described as an electrical shock wave. In a good conductor, there are many free charges available to carry that change along.

In metals, the free charges are free electrons. Each electron moves only a short distance before colliding with atoms or other electrons, so its path looks almost random. An electric field in the conductor gives the electrons a net drift in the direction opposite the field, because electrons are negatively charged.

The average speed of these free charges is called drift velocity. It is measured in meters per second and is very small, often around 10^-4 m/s, because so many free charges are present. Collisions transfer energy to the atoms of the conductor. The electric field does work on the electrons, but that work does not increase their kinetic energy.

The moving charges can be different in different materials. In metals, the charges are electrons. In an ionized gas, or plasma, the moving charges can include both electrons and positively charged ions. In a semiconductor such as silicon, conduction happens partly through electrons and holes, which are empty sites where electrons are missing and that act like positive charges.

Conventional current is treated as the flow of positive charge. This rule is used even when the real moving charges are negative, positive, or both. So in a metallic conductor, electrons move one way, but the current is still drawn in the direction that positive charges would move.

Electrical Current and Electron Drift

electrical current

Current Flow in Simple Circuits

Electrical current is the flow of charge in a circuit. A large current means a large amount of charge moves through a wire in a short time. A small current means only a small amount of charge moves through the circuit over a longer time. Examples include the current needed to run a refrigerator and the smaller current used by a handheld calculator. The SI unit for current is the ampere, or amp. It is named for the French physicist André-Marie Ampère (1775–1836). One ampere means one coulomb of...

drift velocity

Electrical current in a conductor depends on moving charges and the tiny drift speed of those charges. When a free charge enters a wire, it pushes nearby charges ahead because like charges repel each other. That push spreads through the material very quickly, so the electrical signal moves through the system at nearly the speed of light. This fast signal is not the same as the slow motion of each charge. It is a rapidly spreading change in the electric field, often described as an electrical...

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Resistance and Ohm's law help explain how electric current moves through a conductor. In a perfect conductor, the electric field inside is zero because free electrons move to cancel it. Any extra charge then stays on the surface. In a practical conductor, an applied electric field can remain in place. That field drives electrons through the material and creates a current. The current density, which is current per unit area, is related to the electric field. More generally, it is related to the...

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Electron Drift in Metallic Conduction

Electron drift in metallic conduction explains how free electrons move through a conductor. A classical model can describe this motion closely, even though quantum mechanics gives the best overall picture. This model is called the theory of metallic conduction. In this theory, Newton's second law is used to find the acceleration of an electron when an electric field is applied. The electron's velocity is then found from that acceleration. The electron travels through a crystal of positive ions...

key terms and concepts

Learn how electrical current travels through conductors, why electron drift is slow, and how metals, plasma, and semiconductors carry charge.

Electrical Current and Electron Drift | JoVE K12

physics

JoVE Core Física presenta la teoría y la aplicación de conceptos físicos fundamentales, como la cinemática, dinámica, mecánica de fluidos, estática, ondas y acústica, mediante animaciones audiovisuales concisas y fáciles de entender. Además, los vídeos de científicos en acción muestran la aplicación de los conceptos relacionados en experimentos de investigación clásicos y originales, realizados en laboratorios de todo el mundo.

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Tennessee Academic Standards

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PS.9.c

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Alabama Course of Study Science

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Waves and Their Applications in Technologies for Information Transfer

9-12.PS.2.3.c

9-12.PS.2.3.d

9-12.P.2.6.b

9-12.P.2.6.d

Florida Department of Education

SC.912.P.10

SC.912.P.10.15

Texas Essential Knowledge and Skills

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new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Energy

HS-PS3-6.

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PS.PSc.6.4

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Electrical Current and Electron Drift

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