Name: hall voltage and charge carriers
Uploaded: 2025-05-22T09:05:51.000Z
Duration: 1 min 30 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.6.4

The Hall Effect

חשבו על מוליך מלבני נושא זרם עם אלקטרונים כנושאי מטען. כאשר שדה מגנטי מופעל בניצב למישור המוליך, האלקטרונים הנעים בקו ישר נסחפים עקב הכוח המגנטי המסיט אותו.
האלקטרונים מצטברים בצד אחד של המוליך, ומשאירים מטענים חיוביים עודפים בצד השני. הפרדת מטען זו יוצרת שדה חשמלי בתוך המוליך, המפעיל כוח חשמלי על כל אלקטרון המנוגד לכוח המגנטי.
בשיווי משקל, עוצמת הכוח החשמלי מאזנת את הכוח המגנטי, ועוצרת סחף נוסף של האלקטרונים. ההבדל הפוטנציאלי בין שני צידי המוליך הוא מתח האולם.
על ידי ביטוי מהירות הסחיפה במונחים של הזרם, מתח הול יכול לשמש גם כדי למדוד את צפיפות המספרים של נושאי המטען.
גשושיות הול מודדות את עוצמת השדה המגנטי הבלתי ידוע ממתח הול ואת הפרמטרים הידועים של המוליך.
יישום משמעותי של תגלית זו הוא שהקוטביות של מתח הול מרמזת אם נושאי המטען במוליך הם שליליים או חיוביים.

<ol>
	<li>OpenStax. (2019). פיזיקה אוניברסיטאית כרך 2. [גרסת אינטרנט]. מקור: 514-516 <a href="https://openstax.org/books/university-physics-volume-2/pages/11-6-the-hall-effect">https://openstax.org/books/university-physics-volume-2/pages/11-6-the-hall-effect</a></li>
</ol>

אפקט ההול

<div style="direction:rtl">אדווין הול, בשנת 1879, הגה ניסוי שניתן להשתמש בו כדי לזהות את הקוטביות של נושאי המטען השולטים בחומר מוליך. מנקודת מבט היסטורית, ניסוי זה היה הראשון שהוכיח כי נושאי המטען ברוב המתכות הם שליליים. <img alt="Figure1" src="/files/ftp_upload/13772/13772_Figure_1.png" style="text-align: center"> חשבו על לוח מתכת ברוחב L בשדה מגנטי קבוע. האלקטרונים נעים מימין לשמאל, כך שהכוח המגנטי שהם חווים דוחף את האלקטרונים לקצה העליון של הלוח. זה משאיר עודף מטען שלילי בקצה העליון של הלוח ועוד מטען חיובי בקצה התחתון של הלוח, וכתוצאה מכך שדה חשמלי מכוון מלמטה למעלה. ריכוז המטען בשני הקצוות נבנה עד שנוצר מצב שיווי משקל. בשיווי משקל, הכוח החשמלי על האלקטרונים בכיוון אחד מאוזן על ידי הכוח המגנטי בכיוון ההפוך. תרחיש זה שבו השדות החשמליים והמגנטיים מאונכים זה לזה נקרא מצב חוצה שדות. ניתן לכתוב את הזרם בלוח I במונחים של מהירות הסחיפה, vd ושטח החתך של הלוח, A. הפרש הפוטנציאלים בין קצוות הרצועה, המכונה אחרת מתח הול, ניתן על ידי, <img alt="Equation1" src="/files/ftp_upload/13772/13772_Equation_1.png" style="text-align: center; height: 40px;"> הקוטביות של מתח ההול מראה אם נושאי המטען חיוביים או שליליים. יישום חשוב נוסף של אפקט זה הוא עבור חומרים בעלי צפיפות ידועה של נושאי מטען. מתח הול הנמדד יכול לתת את הערך של שדה מגנטי לא ידוע. במעבדות מחקר שבהן שדות האלקטרומגנטים המשמשים למדידות מדויקות צריכים להיות יציבים ביותר, נעשה שימוש נפוץ "בבדיקה של הול" כחלק מהמעגל האלקטרוני לוויסות השדה.</div>

אדווין ה 'הול, בשנת 1879, המציא ניסוי שניתן להשתמש בו כדי לזהות את הקוטביות של נושאי המטען השולטים במוליך ...

Education

JoVE Core

Physics

פיזיקה

Unit 1

יחידה 1

Magnetic Forces and Fields

כוחות ושדות מגנטיים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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 charge at the bottom. As a result, an electric field forms from the bottom edge to the top edge.

The charge buildup continues until equilibrium is reached. At that point, the electric force on the electrons balances the magnetic force in the opposite direction. This is called a crossed-field situation because the electric and magnetic fields are perpendicular to each other. The current in the slab, I, can be written in terms of the drift velocity, v d, and the cross-sectional area, A.

The potential difference between the two edges is called the Hall voltage. Its polarity reveals whether the charge carriers are positive or negative. When the density of charge carriers is known, the Hall voltage can also be used to find an unknown magnetic field. In research labs, a Hall probe is often used in electronic circuits to help regulate electromagnet fields so they stay steady for precise measurements.

Hall Voltage and Charge Carriers

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

Magnetic Force on Moving Charges

Magnetic force on moving charges depends on motion, charge, and field direction. A moving charge or a current creates a magnetic field in the space around it, along with its electric field. That magnetic field can then push on other moving charges or currents in the field. A magnetic field is a vector field, so it has direction as well as strength. At any point, the field direction is the direction a compass needle’s north pole points. The field strength is defined from the force a charged...

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

Magnetic flux through a surface describes how much magnetic field passes across that surface. It is measured in weber (Wb), the SI unit for magnetic flux. Magnetic flux is a scalar quantity, not a vector. Three factors shape magnetic flux. They are the magnetic field strength B, the area the field crosses, and the orientation of the field relative to the surface. For a small area element dA, the flux depends on the part of the magnetic field that is normal, or perpendicular, to that element at...

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-on-current-carrying-wires-example

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...

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 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

Learn how Hall voltage forms in a magnetic field, how it reveals charge carrier polarity, and how Hall probes help measure and control magnetic fields.

Hall Voltage and Charge Carriers | JoVE K12

physics

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.

Virginia  Standards of Learning

HIgh School

PS.9

PS.9.d

Alabama Course of Study Science

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Waves and Their Applications in Technologies for Information Transfer

9-12.PS.2.3.b

Position and Displacement

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Average Velocity

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Instantaneous Velocity - I

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Instantaneous Velocity - II

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Average Acceleration

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Instantaneous Acceleration

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Position and Displacement Vectors

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Force and Momentum

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Analyze and interpret data to explain the motion of an object moving with a constant velocity or that is accelerating.

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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Non-ohmic Devices

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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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Boundary Conditions for Current Density

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Obtain, evaluate, and communicate information to explain how current is affected by changes in composition, length, temperature, and diameter of wire.

PS.PSc.6.3

Magnetism

Magnets are commonly found in everyday objects, such as toys, hangers, elevators, doorbells, and computer devices. Experimentation on these magnets shows ...

Magnetic Fields

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Magnetic Force

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Magnetic Force On Current-Carrying Wires: Example

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Faraday's Law

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Lenz's Law

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Faraday Disk Dynamo

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Induced Electric Fields

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Induced Electric Fields: Applications

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PS.PSc.6.5

Analyze motion in terms of speed, velocity, acceleration, and momentum.

Hall Voltage and Charge Carriers

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