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

Physical Science

motion-and-stability-forces-and-interactions

Motion and Stability- Forces and Interactions

PS.PSc.6.5

Faraday Disk Dynamo

ファラデーディスクダイナモは、誘導の原理で動作する直流発電機です。
これは、導電シャフトを介して一定の角速度で回転する導電ディスクで構成され、導電シャフトはディスクの平面に垂直な均一な磁場に配置されます。ディスクの回転は、ディスクに運動的な起電力を誘発します。
ディスクの小さなセグメントに接する速度ベクトルがあるとします。このセグメントの磁力は放射状に外側にあります。これにより、縁に向かって自由な正の電荷が蓄積され、中心に向かって自由な負の電荷が蓄積され、emfが発生します。
emfの方程式をセグメントの長さの限界内で積分し、速度ベクトルの大きさを代入すると、運動emfの大きさが得られます。
このディスクは、閉ループに電流を流す2つの固定ブラシを介して回路に接続できます。
レンツの法則によれば、誘導電流は円盤の一定の角速度に対抗します。そのため、ディスクを一定の角速度で回転させ続けるための作業を行う必要があります。

<ol>
	<li>ヤング、HD、フリードマン、RA(2012)。現代物理学と大学物理学。カリフォルニア州サンフランシスコ:ピアソン。セクション29.4、971ページ。</li>
</ol>

ファラデーのディスクダイナモ

ファラデーのディスク ダイナモは、時間的に一定の起電力を生成する DC 発電機です。 これは、磁場内でディスク面に垂直に一定の角速度で回転する導電性ディスクで構成されています。 ディスクの回転により磁束の変化が生じ、これによって起電力が誘発され、ディスクのリムと中心に反対の電荷が発生します。 誘導起電力の極性は、磁場の方向とディスクの回転方向によって決まります。 回転ディスクがブラシを使用して外部回路に接続されている場合、誘導電流が流れます。

レンツの法則によれば、誘導起電力は常にそれを生み出す原因に対抗します。 ファラデーのディスク ダイナモの場合、誘導起電力がディスクの回転を妨げます。 したがって、ディスクを一定の角速度で回転し続けるには、外部電力を供給する必要があります。

このような発電機での誘導起電力は、数ミリボルトから数ボルトの範囲になります。 誘導起電力の大きさは、複数の発電機を直列に接続するか、磁場の強度、ディスクの半径、ディスクの角速度を増加させることによってさらに高めることができます。

ファラデーディスクダイナモはDC発電機であり、時間的に一定の起電力を生成します。それは一定の角度で回転する導電ディスクで構成されています...

Education

JoVE Core

Physics

物理学

Unit 1

ユニット1

Electromagnetic Induction

電磁誘導

KEY TERMS AND CONCEPTS

主要用語と概念

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

Magnetic Flux and Induced Current

Magnetic flux and induced current are linked when a magnetic field changes near a coil. Moving a bar magnet into or out of a coil induces an emf, which is an electromotive force. If the motion goes in the opposite direction, the emf has the opposite sign. Reversing the magnet poles also reverses the direction of the induced emf. The same effect appears when the coil moves instead of the magnet. Relative motion is what matters. A faster motion produces a larger emf. If the magnet and coil stay...

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faraday's law

Magnetic Flux and Induced Emf

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lenz's law

Magnet Motion and Induced Current

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motional emf

Induced Current from Changing Magnetic Flux

Induced current from changing magnetic flux depends on how a magnetic field interacts with an area. Magnetic flux changes when the field strength changes, when the area it passes through changes, or when the field turns relative to the surface. When any of these factors vary, the magnetic flux also varies. A change in area can happen in two common ways. The flux through a rectangular loop increases as the loop moves into a magnetic field. The magnetic flux through a rotating coil also changes...

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...

induced electric fields

Faraday’s Law and Induced EMF

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induced electric fields: applications

Electric Fields from Changing Magnetism

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Maxwell’s Fix for Changing Currents

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Maxwell’s Fix for Charging Capacitors

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electromagnetic fields

Electric and Magnetic Fields in Motion

Electric and magnetic fields can come from different sources, but they can act in surprisingly similar ways. Static charges create electrostatic fields. These fields are conservative, which means a test charge does no net work after moving around a complete loop. Fields made by changing magnetic fields behave differently. They are not conservative, and they do net work on a charge. That work is proportional to how fast the magnetic flux changes. These fields also do not follow Gauss’s law for...

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Maxwell's Equations and Light Waves

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Electric and Magnetic Field Symmetry

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electric generator: alternator

How Alternators Produce AC Power

Alternators produce alternating current by rotating a conducting loop in a magnetic field. As the loop turns inside the field, the magnetic flux through the coil changes with time. That changing flux induces an emf, or electric voltage, in the circuit. A simple alternator uses a loop placed in a uniform magnetic field. The loop connects to split rings, and brushes carry the current to the external circuit. As the loop rotates, the magnetic flux changes sinusoidally, so the induced emf also...

back emf

Motor Current and Speed Changes

Motor current and speed changes are linked by back emf in an electric motor. A motor sends current through a wire loop in a magnetic field. The magnetic field pushes on the loop and creates torque, which turns a shaft and does mechanical work. As the coil turns, the magnetic flux through it changes. That changing flux induces an emf, or voltage, by Faraday’s law. The motor then acts like a generator whenever its coil rotates, whether the shaft is turned by an external drive or by the motor...

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

physics

JoVE Core 物理学は、運動学、力学、流体力学、静力学、波動、音響などの基礎的な物理学の理論と応用を、簡潔でわかりやすいアニメーション ビデオで紹介します。さらに、科学者の実際のビデオでは、世界中の今日の研究所で行われている古典的および独自の研究実験における関連概念の適用を示しています。

PS.Phy.5.2

Position and Displacement

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Average Velocity

To calculate the other physical quantities in kinematics, we must introduce the time variable. The time variable allows us not only to state the position ...

Instantaneous Velocity - I

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Instantaneous Velocity - II

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Average Acceleration

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Instantaneous Acceleration

Acceleration is in the direction of the change in velocity, but it is not always in the direction of motion. When an object slows down, its acceleration ...

Position and Displacement Vectors

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Average and Instantaneous Velocity Vectors

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PS.PSc.4.1

Electrical Current

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Drift Velocity

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Current Density

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Resistivity

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Resistance

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Ohm's Law

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Construct an explanation to compare simple series and parallel circuits in terms of Ohm's Law.

PS.PSc.6.2

Continuity Equation

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PS.PSc.6.3

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motion-of-a-charged-particle-in-a-magnetic-field

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Magnetic Force On A Current-Carrying Conductor

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Magnetic Force On Current-Carrying Wires: Example

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Force On A Current Loop In A Magnetic Field

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PS.PSc.6.4

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Faraday Disk Dynamo and DC Output

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