Name: eddy currents and magnetic braking
Uploaded: 2023-09-18T17:11:20.000Z
Duration: 1 min 17 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Physics

motion-and-stability-forces-and-interactions

Motion and Stability- Forces and Interactions

PS.Phy.5.2

Magnetic Damping

Considere una placa metálica fijada a un extremo que se balancea libremente alrededor de su posición media, colocada entre dos electroimanes.
Cuando no hay campo magnético, la placa sigue oscilando. Una vez que se encienden los electroimanes, la placa se ralentiza y se detiene rápidamente.
Esta reducción del movimiento sin ningún contacto físico se denomina amortiguación magnética, causada por la naturaleza opuesta de las corrientes de Foucault.
Ahora vuelve a girar el plato para entender este mecanismo.
Cuando la placa entra en el campo magnético, el flujo magnético en la placa cambia.
Según la ley de Faraday, las corrientes de Foucault se inducen en la placa y, de acuerdo con la ley de Lenz, su dirección es en sentido contrario a las agujas del reloj. Por lo tanto, la placa experimenta una fuerza magnética que se opone a su movimiento.
De manera similar, cuando la placa sale del campo magnético, el flujo magnético disminuye y las corrientes de Foucault se inducen en el sentido de las agujas del reloj.
Como resultado, la placa vuelve a experimentar una fuerza magnética que se opone a su salida del campo magnético.
Así, como efecto combinado, las oscilaciones de la placa metálica se amortiguan rápidamente.

<ol>
	<li>OpenStax. (2019). Física Universitaria Vol. 2. [Versión web]. Obtenido de <a href="https://openstax.org/books/university-physics-volume-2/pages/13-5-eddy-currents">https://openstax.org/books/university-physics-volume-2/pages/13-5-eddy-currents</a></li>
</ol>

amortiguación magnética

Las corrientes de Eddy pueden producir una importante resistencia al movimiento, llamada amortiguación magnética. Por ejemplo, cuando un péndulo metálico oscila entre los polos de un imán fuerte, actúa una resistencia significativa sobre el péndulo a medida que entra y sale del campo, amortiguando rápidamente el movimiento. Sin embargo, si el péndulo es una placa metálica ranurada, el imán produce un efecto mucho menor. Cuando una placa metálica ranurada entra en el campo, se induce una FEM debido al cambio en el flujo; sin embargo, su eficacia es menor porque las ranuras limitan el tamaño de las corrientes. Además, las corrientes en las ranuras adyacentes tienen direcciones opuestas y sus efectos se cancelan. Cuando se utiliza un material aislante, la corriente de Eddy es extremadamente pequeña, por lo que la amortiguación magnética en los aislantes es insignificante. Si se quieren evitar las corrientes de Eddy en conductores, deben tener ranuras o estar construidos con capas delgadas de material conductor separadas por hojas aislantes. La amortiguación magnética se utiliza en balanzas de laboratorio sensibles. Para tener la máxima sensibilidad y precisión, la balanza debe tener la menor fricción posible. Si es libre de fricción, oscila durante mucho tiempo. La amortiguación magnética es una solución simple e ideal. Con la amortiguación magnética, la resistencia es proporcional a la velocidad y se vuelve cero a velocidad cero. Así, las oscilaciones se amortiguan rápidamente, después de lo que la fuerza de amortiguación desaparece, permitiendo que la balanza sea muy sensible. En la mayoría de las balanzas, la amortiguación magnética se logra con un disco conductor que gira en un campo fijo.

Amortiguación magnética

Las corrientes de Foucault pueden producir una resistencia significativa en el movimiento, llamada amortiguación magnética. Por ejemplo, cuando un péndulo metálico oscila entre los polos de un ...

Education

Educación

JoVE Core

Física

Unit 1

Unidad 1

Electromagnetic Induction

Inducción electromagnética

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

eddy currents and magnetic braking

Eddy currents can create strong drag on moving objects. This drag is called magnetic damping. A metallic pendulum bob swinging between the poles of a strong magnet feels this force as it enters and leaves the field, so its motion dies out quickly.

The effect is much smaller for a slotted metal plate. As the plate enters the magnetic field, a changing flux induces an emf, or electromotive force. The slots limit the size of the current loops, and nearby loops can carry currents in opposite directions, so their effects cancel.

Insulating materials behave differently. Their eddy currents are extremely small, so magnetic damping on insulators is negligible. If eddy currents must be reduced in conductors, the material can be slotted or made from thin conducting layers separated by insulating sheets.

Magnetic damping is useful in sensitive laboratory balances. These balances need to be as friction-free as possible for maximum sensitivity and accuracy. A friction-free balance can oscillate for a long time, so magnetic damping provides a simple solution. The drag is proportional to speed and drops to zero when the object stops moving, which quickly calms the motion while keeping the balance sensitive. In most balances, this is done with a conducting disc rotating in a fixed magnetic field.

Eddy Currents and Magnetic Braking

induction

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magnetic damping

Eddy currents can create strong drag on moving objects. This drag is called magnetic damping. A metallic pendulum bob swinging between the poles of a strong magnet feels this force as it enters and leaves the field, so its motion dies out quickly. The effect is much smaller for a slotted metal plate. As the plate enters the magnetic field, a changing flux induces an emf, or electromotive force. The slots limit the size of the current loops, and nearby loops can carry currents in opposite...

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An electric field can be induced by a changing magnetic field. This induced electric field is nonconservative, which means it does not do net work when a charge moves around a closed path. That behavior is different from an electrostatic field, which comes from a fixed charge distribution. An electrostatic field is conservative, so it does no net work over a closed path. Because of this difference, electric potential can be linked to the electrostatic field, but not to the induced field. When...

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Eddy currents affect how metals move, stop, and heat up. They form only in conductors, so they are useful for separating metals from nonmetals and for other practical devices. In recycling centers, trash can be sent down a ramp under a strong magnet. Metals in the trash slow down because eddy currents resist their motion. Nonmetals keep moving, so the materials separate. This method works for metals in general, not only ferromagnetic ones. Eddy currents also help in metal detectors. A...

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electromagnetic fields

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symmetry in maxwell's equations

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electric generator: alternator

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back emf

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key terms and concepts

Learn how eddy currents create magnetic damping, why slotted plates reduce the effect, and how balances use it to improve sensitivity and accuracy.

Eddy Currents and Magnetic Braking | JoVE K12

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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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Eddy Currents and Magnetic Braking

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