Name: faraday disk dynamo and dc output
Uploaded: 2023-09-18T17:11:16.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Physical Science

motion-and-stability-forces-and-interactions

Motion and Stability- Forces and Interactions

PS.PSc.6.5

Faraday Disk Dynamo

La dinamo a disco di Faraday è un generatore di corrente continua che funziona secondo il principio dell'induzione.
È costituito da un disco conduttore che ruota con una velocità angolare costante tramite un albero conduttore, che è posto in un campo magnetico uniforme perpendicolare al piano del disco. La rotazione del disco induce in esso una forza elettromagnetica motrice.
Si consideri un piccolo segmento del disco con un vettore di velocità tangente ad esso. La forza magnetica su questo segmento è radialmente verso l'esterno. Questo accumula cariche positive libere verso il bordo e cariche negative libere verso il centro, risultando in campi elettromagnetici.
Integrando l'equazione della f.e.m. entro i limiti della lunghezza del segmento e sostituendo la grandezza del vettore di velocità si ottiene la grandezza della f.e.m. di movimento.
Questo disco può essere collegato al circuito tramite due spazzole fisse, che conducono la corrente attraverso l'anello chiuso.
Secondo la legge di Lenz, la corrente indotta si oppone alla velocità angolare costante del disco. Quindi, è necessario lavorare per mantenere il disco in rotazione a velocità angolare costante.

<ol>
	<li>Young, H.D e Freedman, R.A. (2012). Fisica universitaria con fisica moderna. San Francisco, CA: Pearson. Sezione 29.4, pagine 971.</li>
</ol>

dinamo a disco di faraday

Una dinamo a disco di Faraday è un generatore di corrente continua che produce una fem costante nel tempo. Consiste in un disco conduttore che ruota con una velocità angolare costante nel campo magnetico, perpendicolarmente al piano del disco. La rotazione del disco provoca una variazione del flusso magnetico, che induce una fem, causando lo sviluppo di cariche opposte sul bordo e al centro del disco. La polarità della fem indotta può essere determinata dalla direzione del campo magnetico e dalla direzione della rotazione del disco. Se il disco rotante è collegato a un circuito esterno tramite spazzole, allora fluisce una corrente indotta.

Secondo la legge di Lenz, la fem indotta si oppone sempre alla causa che la produce. Per la dinamo a disco di Faraday, la fem indotta contrasta la rotazione del disco. Pertanto, deve essere fornita energia esterna per mantenere il disco in rotazione con una velocità angolare costante.

La fem indotta in una tale dinamo può variare da alcuni millivolt a alcuni volt. La magnitudine della fem indotta può essere ulteriormente aumentata collegando più generatori in serie o aumentando la forza del campo magnetico, il raggio del disco e la velocità angolare del disco.

Dinamo a disco di Faraday

Una dinamo a disco di Faraday è un generatore di corrente continua, che produce una f.e.m. costante nel tempo. È costituito da un disco conduttore che ruota con una ghiera angolare costante ...

Education

Didattica

JoVE Core

Physics

Fisica

Unit 1

Unità 1

Electromagnetic Induction

Induzione elettromagnetica

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

faraday disk dynamo and dc output

A Faraday disk dynamo is a DC generator that produces an emf constant in time. It uses a conducting disk that spins at constant angular velocity in a magnetic field. The magnetic field is perpendicular to the plane of the disk.

As the disk rotates, the magnetic flux changes and an emf is induced. This causes opposite charges to build up at the rim and at the center of the disk. The direction of the induced emf depends on the direction of the magnetic field and the direction of rotation.

If brushes connect the rotating disk to an external circuit, an induced current flows. Lenz’s law explains that the induced emf opposes the cause that creates it. In this case, the emf opposes the rotation of the disk, so outside power is needed to keep the disk moving at a constant angular velocity.

The induced emf in a Faraday disk dynamo can range from a few millivolts to a few volts. Its size can be increased by connecting multiple generators in series. It can also be raised by using a stronger magnetic field, a larger disk radius, or a faster disk rotation.

Faraday Disk Dynamo and DC Output

induction

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faraday disk dynamo

A Faraday disk dynamo is a DC generator that produces an emf constant in time. It uses a conducting disk that spins at constant angular velocity in a magnetic field. The magnetic field is perpendicular to the plane of the disk. As the disk rotates, the magnetic flux changes and an emf is induced. This causes opposite charges to build up at the rim and at the center of the disk. The direction of the induced emf depends on the direction of the magnetic field and the direction of rotation. If...

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induced electric fields: applications

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key terms and concepts

Learn how a Faraday disk dynamo makes steady DC output, builds charge on the disk, and uses Lenz’s law to resist rotation.

Faraday Disk Dynamo and DC Output | JoVE K12

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Faraday Disk Dynamo and DC Output

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