Name: factors that affect electrical resistance
Uploaded: 2023-04-30T12:39:00.000Z
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K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Physical Science

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Motion and Stability- Forces and Interactions

PS.PSc.6.2

Resistance

Lorsqu'un courant circule dans un circuit, les collisions entre les électrons et les atomes dans le fil provoquent une résistance au mouvement des électrons, mesurée en ohms.
La résistance électrique d'un circuit est le rapport entre la tension appliquée et le courant qui le traverse. La résistance dépend également de la résistivité du matériau et est équivalente à la résistivité du matériau multipliée par la longueur divisée par la section transversale du fil.
La température influence la résistance des matériaux et peut être modélisée à l’aide de l’équation de résistivité.
Un composant d’un circuit qui réduit le flux de courant est connu sous le nom de résistance, représenté par deux symboles fournis par l’American National Standard Institute et la Commission électrotechnique internationale.
Le carbone est le matériau le plus couramment utilisé pour fabriquer des résistances. Les pistes en carbone sont enroulées autour d’un noyau en céramique, qui est relié à deux fils de cuivre et marqué de quatre bandes pour identifier la résistance.
Les deux premières bandes colorées représentent les deux premiers chiffres de la résistance, tandis que les troisième et quatrième couleurs représentent son multiplicateur et sa tolérance.

<ol>
	<li>OpenStax. (2019). Physique universitaire Vol. 2. [Version Web], p. 396 à 398. Récupéré de <a href="https://openstax.org/books/university-physics-volume-2/pages/9-3-resistivity-and-resistance">https://openstax.org/books/university-physics-volume-2/pages/9-3-resistivity-and-resistance</a></li>
</ol>

résistance

Lorsqu'un courant circule à travers n'importe quel conducteur, le conducteur crée une certaine difficulté au courant de circuler. La mesure de cette difficulté est appelée résistance du matériau et est représentée par R. Chaque matériau a sa propre résistance. Dans le cas des conducteurs, de la chaleur est émise chaque fois qu'un courant les traverse. La résistance dépend de la résistivité du matériau. La résistivité est une caractéristique du matériau utilisé pour fabriquer les composants électriques, tandis que la résistance est une caractéristique du composant lui-même.

Pour calculer la résistance, considérez une section de fil conducteur avec une aire de section transversale A, une longueur L et une résistivité ρ. Une batterie est connectée à travers le conducteur, fournissant une différence de potentiel ΔV à travers celui-ci. La différence de potentiel produit un champ électrique qui est proportionnel à la densité de courant :

<img alt="Equation1" src="/files/ftp_upload/13747/13747_Equation_1.svg" style="text-align: center; height: 13px;" />

La magnitude du champ électrique à travers un segment du conducteur est égale à la tension divisée par la longueur, et la magnitude de la densité de courant est égale au courant divisé par l'aire de section transversale. En substituant les valeurs et en rappelant que le champ électrique est proportionnel à la résistivité et à la densité de courant, on peut établir une relation entre la tension et le courant :

<img alt="Equation2" src="/files/ftp_upload/13747/13747_Equation_2.svg" style="text-align: center; height: 26px;" />

La résistance d'un matériau peut être définie comme le rapport de la tension au courant qui le traverse et est représentée en ohms. La résistance d'un segment cylindrique d'un conducteur est égale à la résistivité du matériau multipliée par la longueur divisée par l'aire :

<img alt="Equation3" src="/files/ftp_upload/13747/13747_Equation_3.svg" style="text-align: center; height: 26px;" />

La résistance d'un objet dépend également de la température. Pour un cylindre donné, si la longueur et l'aire ne varient pas beaucoup avec la température, la résistance du matériau a la même dépendance en température que la résistivité :

<img alt="Equation4" src="/files/ftp_upload/13747/13747_Equation_4.svg" style="text-align: center; height: 13px;" />

où R0 est la résistance d'origine à température ambiante, R est la résistance après un changement de température, et α est le coefficient de température du matériau.<img height="20" src="file:///C:/Users/TIMOTH~1/AppData/Local/Temp/msohtmlclip1/01/clip_image006.gif" width="10" />

Résistance

Lorsqu’un courant se déplace à travers un conducteur, le conducteur provoque un certain niveau de difficulté pour que le courant circule. La mesure de cette difficulté est connue...

Education

Enseignement

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Physics

Physique

Unit 1

Unité 1

Current and Resistance

Courant et résistance

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

factors that affect electrical resistance

Electrical resistance describes how much a conductor opposes the flow of current. It is represented by R. When current passes through a conductor, heat is also produced. Resistance is tied to the material’s resistivity, which is a property of the material used to make an electrical component.

Resistance is different from resistivity. Resistivity belongs to the material itself, while resistance belongs to the finished component. To study this relationship, consider a wire with length L, cross-sectional area A, and resistivity ρ. If a battery provides a potential difference ΔV across the wire, the voltage creates an electric field in the conductor.

The electric field across the wire segment equals the voltage divided by the length. The current density equals the current divided by the cross-sectional area. Because the electric field is proportional to resistivity and current density, these values can be combined to relate voltage and current. Resistance is then defined as the ratio of voltage to current and is measured in ohms.

For a cylindrical conductor, resistance equals resistivity multiplied by length divided by area. Resistance also changes with temperature. If the length and area stay nearly the same as temperature changes, the resistance follows the same temperature dependence as the resistivity. In that case, R0 is the original resistance at room temperature, R is the resistance after the temperature change, and α is the temperature coefficient of the material.

Factors That Affect Electrical Resistance

factors-that-affect-electrical-resistance

electrical current

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resistivity

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resistance

Electrical resistance describes how much a conductor opposes the flow of current. It is represented by R. When current passes through a conductor, heat is also produced. Resistance is tied to the material’s resistivity, which is a property of the material used to make an electrical component. Resistance is different from resistivity. Resistivity belongs to the material itself, while resistance belongs to the finished component. To study this relationship, consider a wire with length L,...

ohm's law

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key terms and concepts

Learn how resistance depends on resistivity, wire length, cross-sectional area, voltage, current, and temperature in conductors and electrical circuits.

Factors That Affect Electrical Resistance | JoVE K12

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Waves and Their Applications in Technologies for Information Transfer

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Factors That Affect Electrical Resistance

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