Name: balancing weight with magnetic force
Uploaded: 2025-05-22T09:05:51.000Z
Duration: 1 min 22 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.6.4

magnetic-force-on-current-carrying-wires-example

Magnetic Force On Current-Carrying Wires: Example

Stellen Sie sich einen Leiter in der XY-Ebene vor, der Strom nach links führt. Der Leiter besteht aus zwei geraden Segmenten mit einer Länge von L parallel zur x-Achse und einem Halbkreis mit einem Radius von R.
Wenn der Leiter in einem gleichmäßigen Magnetfeld senkrecht zur Ebene des Drahtes nach außen gerichtet ist, bestimmen Sie die gesamte Magnetkraft auf den Leiter.
Ermitteln Sie zunächst die Magnetkraft für die einzelnen geraden Abschnitte, die in x-Richtung Strom führen.
Zweitens teile das gekrümmte Segment in unendlich kleine gerade Abschnitte mit einer Länge von dl in einem Winkel von Theta auf.
Die infinitesimale Länge und das Magnetfeld stehen senkrecht zueinander, und die Richtung ihres Kreuzprodukts ist radial nach außen. So können die Größe und die Komponenten der Kraft, die auf die Abschnitte einwirkt, bestimmt werden.
Durch die Integration des Ausdrucks in Bezug auf Theta kann die Kraft auf den gesamten gekrümmten Leiter bestimmt werden.
Schließlich kann durch Addieren der Kräfte auf alle drei Abschnitte die Gesamtkraft auf den Leiter in positiver y-Richtung erhalten werden.

<ol>
	<li>OpenStax. (2019). Universitätsphysik Vol. 2. [Web-Version], Seite 396 - 398. Abgerufen von <a href="https://openstax.org/books/university-physics-volume-2@8ede2ba/pages/11-4-magnetic-force-on-a-current-carrying-conductor">https://openstax.org/books/university-physics-volume-2@8ede2ba/pages/11-4-magnetic-force-on-a-current-carrying-conductor</a></li>
</ol>

magnetische kraft auf stromführende drähte: beispiel

In einem Magnetfeld treffen bewegte Ladungen auf eine Kraft. Wenn ein Draht diese bewegten Ladungen enthält, d.h. wenn der Draht einen Strom führt, wirkt auch eine Kraft auf den Draht. Betrachten Sie ein Paar flexibler Leitungen, die einen Draht halten, der 40 cm lang und 10 g schwer ist und sich in horizontaler Position befindet. Der Draht wird in einem konstanten Magnetfeld von 0,40 T platziert, wie in Abbildung 1(a) dargestellt. Bestimmen Sie die Größe und Richtung des Stroms, der durch den Draht fließen muss, um die Spannung in den unterstützenden Leitungen zu beseitigen.

Um das Problem zu lösen, zeichnen Sie zunächst ein Kräftegleichgewichtsdiagramm des Systems, wie in Abbildung 1(b) dargestellt. Verwenden Sie dann die Rechte-Hand-Regel, um die Richtung der magnetischen Kraft auf den Draht zu bestimmen. Setzen Sie schließlich die beiden Kräfte gleich, um den Strom im Draht zu bestimmen.

<img alt="Equation1" src="/files/ftp_upload/13769/13769_Figure_1.png" style="text-align: center;" />

In einem Kräftegleichgewichtsdiagramm ist die Spannung in den unterstützenden Leitungen null, wenn die magnetische und die gravitative Kräfte ausgeglichen sind. Durch Verwendung der Rechte-Hand-Regel zeigt die magnetische Kraft nach oben, und durch Gleichsetzen der beiden Gewichts- und magnetischen Kräfte auf den Draht:

<img alt="Equation2" src="/files/ftp_upload/13769/13769_Equation_2.svg" style="text-align: center; height: 20px;" />

<img alt="Equation3" src="/files/ftp_upload/13769/13769_Equation_3.svg" style="text-align: center; height: 50px;" />

Der Strom im Draht kann bestimmt werden. Das große Magnetfeld erzeugt eine signifikante Kraft auf eine Drahtlänge, um das Gewicht des Drahts auszugleichen.

Magnetische Kraft auf stromführende Drähte: Beispiel

In einem Magnetfeld treffen bewegte Ladungen auf eine Kraft. Enthält ein Draht diese beweglichen Ladungen, d.h. wenn der Draht einen Strom führt, dann wirkt eine Kraft ...

Education

Lehre

JoVE Core

Physics

Physik

Unit 1

Einheit 1

Magnetic Forces and Fields

Magnetische Kräfte und Felder

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

balancing weight with magnetic force

Magnetic force can balance the weight of a current-carrying wire when the wire sits in a magnetic field. Moving charges in the wire feel a force, so the wire itself can be pushed upward or downward. This example uses a flexible wire that is 40 cm long and has a mass of 10 g. It is held in a horizontal position inside a constant 0.40 T magnetic field.

The goal is to find the current needed to remove the tension in the supporting leads. To do that, a free-body diagram is drawn first. The diagram shows the forces acting on the wire. Then the right-hand rule is used to find the direction of the magnetic force on the wire.

When the tension in the leads is zero, the magnetic force and the gravitational force are balanced. The magnetic force points up, so it can counter the wire’s weight. By setting the weight equal to the magnetic force, the current in the wire can be determined. The strong magnetic field produces a large enough force on the wire to support its weight.

Balancing Weight with Magnetic Force

magnetism

Magnetic Poles and Everyday Uses

Magnetism appears in many everyday objects, from toys and hangers to elevators, doorbells, and computer devices. Magnets have two poles, called north and south. Like poles repel each other, while unlike poles attract. Both poles can also attract unmagnetized iron. A single magnetic pole cannot be isolated, because every part of a magnet contains both a north pole and a south pole. A compass needle is a simple example of a magnet. It is a thin bar magnet suspended at its center, so it can turn...

magnetic fields

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magnetic field lines

Reading Magnetic Field Lines

Magnetic field lines show the direction and strength of a magnetic field. They make it easier to picture how a magnet acts in space. Each line forms a closed loop around the magnet. For a bar magnet, the field lines leave the north pole and curve around to the south pole. They then continue through the magnet back to the north pole. This loop has no beginning or end. Magnetic field lines follow clear rules. The magnetic field points tangent to a field line at any point. A small compass points...

magnetic flux

Magnetic Flux Through Surfaces

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motion of a charged particle in a magnetic field

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

Charged Particle Paths in Magnetic Fields

A charged particle in a magnetic field follows a path that depends on the direction of its velocity. When the field is uniform and the particle moves perpendicular to it, the magnetic field is the main factor that controls the motion, especially in a vacuum. The magnetic force is always perpendicular to the direction of motion, so the particle curves into a circle. Because the force stays perpendicular to velocity, it does no work on the particle. The kinetic energy and speed stay constant...

magnetic force

Magnetic Fields and Moving Charges

Magnetic fields and moving charges create magnetic force. A moving electric charge, or a current made of many moving charges, produces a magnetic field. When another current or moving charge enters that field, it feels a magnetic force in response. At the atomic level, magnetic forces come from interactions between moving electrons in the atoms of two bodies. The strength of magnetic force depends on several factors. It increases with the size of the charge and with the strength of the...

magnetic force on a current-carrying conductor

magnetic-force-on-a-current-carrying-conductor

Current and Magnetic Field Around a Wire

A current-carrying wire creates a magnetic field around it, and moving charges feel a force in that field. Because the magnetic field produced by moving charges is proportional to current, the wire itself acts as a source of magnetic field. A compass placed near the wire shows this effect by lining up tangentially around the wire. The magnetic field around a straight wire forms concentric circular loops. The right-hand rule helps determine the direction of those loops. If the thumb points in...

magnetic force on current-carrying wires: example

Magnetic force can balance the weight of a current-carrying wire when the wire sits in a magnetic field. Moving charges in the wire feel a force, so the wire itself can be pushed upward or downward. This example uses a flexible wire that is 40 cm long and has a mass of 10 g. It is held in a horizontal position inside a constant 0.40 T magnetic field. The goal is to find the current needed to remove the tension in the supporting leads. To do that, a free-body diagram is drawn first. The diagram...

force on a current loop in a magnetic field

force-on-a-current-loop-in-a-magnetic-field

Current Loops and Torque in Motors

Current loops in a magnetic field create the torque that drives a DC motor. A DC motor converts electrical energy into mechanical work. In a motor, wire loops sit inside a magnetic field. When current flows through the loops, the magnetic field pushes on them and makes the shaft rotate. The current is reversed when the loop lines up with the magnetic field. This keeps the torque on the loop going in the same direction. A commutator and brushes handle this reversal. The commutator switches the...

torque on a current loop in a magnetic field

torque-on-a-current-loop-in-a-magnetic-field

Current Loop Torque in Electric Motors

Current loop torque in electric motors shows how magnetic force can make a wire loop rotate. In an electric motor, loops of wire sit between magnets in a magnetic field. When current flows through the loops, the field applies torque. This rotation turns a shaft and converts electrical energy into mechanical energy. A rectangular current-carrying loop with N turns in a uniform magnetic field has zero net force. Even so, it can still experience net torque. The torque depends on the current I,...

the hall effect

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...

thomson's e/m experiment

Electron Speed Selector in Thomson’s Tube

A velocity selector uses electric and magnetic fields to choose charged particles with one speed from a beam. Many beams from a heated cathode contain particles moving at different speeds, so this setup helps produce a uniform beam. The electric and magnetic fields are perpendicular to the particle’s motion and to each other. In this arrangement, a particle with charge q, speed v, and mass m enters from the top. The magnetic field points into the plane of the paper, and the electric field...

key terms and concepts

Find out how a current-carrying wire can be supported by a magnetic field. Use a free-body diagram and the right-hand rule to solve for current.

Balancing Weight with Magnetic Force | JoVE K12

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JoVE Core Physics introduces the theory and application of fundamental physics topics, including kinematics, dynamics, fluid mechanics, statics, waves, and acoustics, with concise and easy-to-understand animated videos. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

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Ohio’s Learning Standards and Model Curriculum

Electricity And Magnetism

Electromagnetic interactions

Tennessee Academic Standards

High School

Energy

PHYS.PS3.9

Virginia  Standards of Learning

HIgh School

PS.9

PS.9.d

PH.7

PH.7.a

PH.7.b

Alabama Course of Study Science

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Waves and Their Applications in Technologies for Information Transfer

9-12.PS.2.3.b

Florida Department of Education

SC.912.P.10

SC.912.P.10.10

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PS.PSc.6.3

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PS.PSc.6.5

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Balancing Weight with Magnetic Force

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