Name: factors that affect electrical resistance
Uploaded: 2023-04-30T12:39:00.000Z
Duration: 1 min 19 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.6.2

Resistance

Bir devreden bir akım geçtiğinde, teldeki elektronlar ve atomlar arasındaki çarpışmalar, ohm cinsinden ölçülen elektronların hareketine dirence neden olur.
Bir devrenin elektrik direnci, uygulanan voltajın içinden geçen akıma oranıdır. Direnç aynı zamanda malzemenin direncine de bağlıdır ve malzemenin direncinin çarpımı uzunluğun telin kesit alanına bölünmesine eşdeğerdir.
Sıcaklık, malzemelerin direncini etkiler ve özdirenç denklemi kullanılarak modellenebilir.
Akım akışını azaltan bir devredeki bir bileşen, Amerikan Ulusal Standartlar Enstitüsü ve Uluslararası Elektroteknik Komisyonu tarafından sağlanan iki sembolle temsil edilen bir direnç olarak bilinir.
Karbon, direnç yapmak için kullanılan en yaygın malzemedir. Karbon izler, direnci tanımlamak için iki bakır uca bağlanan ve dört bantla işaretlenen seramik bir çekirdeğin etrafına sarılır.
İlk iki renkli bant, direncin ilk iki basamağını temsil ederken, üçüncü ve dördüncü renkler çarpanını ve toleransını temsil eder.

<ol>
	<li>Stax'ı açın. (2019). Üniversite Fiziği Cilt 2. [Web versiyonu], Sf 396–398. <a href="https://openstax.org/books/university-physics-volume-2/pages/9-3-resistivity-and-resistance" adresinden alındı>https://openstax.org/books/university-physics-volume-2/pages/9-3-resistivity-and-resistance</a></li>
</ol>

direnç

Bir akım herhangi bir iletken içinden geçtiğinde, iletken akımın akmasına bazı zorluklar çıkartır. Bu zorluk ölçüsü malzemenin direnci olarak bilinir ve R ile temsil edilir. Her malzemenin kendi direnci vardır. İletkenlerin durumunda, bir akım geçtiğinde ısınma meydana gelir. Direnç malzemenin direncine bağlıdır. Direnç malzemenin elektriksel bileşenlerin yapımında kullanılan bir özelliği iken, direnç bileşenin kendisinin bir özelliğidir.

Direnç hesaplaması için, kesitin alanı A, uzunluğu L ve direnç ρ olan bir iletken tel parçası düşünün. Bir pil, iletkenin üzerinden geçen bir potansiyel farkı sağlayarak, ileti arasındaki bir fark sağlar. Potansiyel fark elektriksel bir alanı sağlar ve bu alan, akım yoğunluğuyla orantılıdır:

<img alt="Equation1" src="/files/ftp_upload/13747/13747_Equation_1.svg" style="text-align: center; height: 13px;" />

İletkenin bir bölümündeki elektrik alanının büyüklüğü gerilim ile uzunluğun bölümüne eşittir ve elektrik akımı yoğunluğunun büyüklüğü akımın kesit alanına bölünmesine eşittir. Değerler yerine konulduğunda ve elektriksel alanın direnci ve akım yoğunluğuna orantılı olduğu hatırlanarak, gerilim ve akım arasında bir ilişki kurulabilir:

<img alt="Equation2" src="/files/ftp_upload/13747/13747_Equation_2.svg" style="text-align: center; height: 26px;" />

Bir malzemenin direnci, üzerinden geçen akımın gerilime oranı olarak tanımlanabilir ve ohm cinsinden temsil edilir. İletkenin silindirik bir bölümünün direnci, malzemenin direncinin uzunlukla çarpımının alanla bölünmesine eşittir:

<img alt="Equation3" src="/files/ftp_upload/13747/13747_Equation_3.svg" style="text-align: center; height: 26px;" />

Nesnenin direnci aynı zamanda sıcaklığa bağlıdır. Verilen bir silindir durumunda, eğer uzunluk ve alan sıcaklıkla çok fazla değişmezse, malzemenin dirençsizlik özelliği de aynı sıcaklık bağımlığına sahip olur:

<img alt="Equation4" src="/files/ftp_upload/13747/13747_Equation_4.svg" style="text-align: center; height: 13px;" />

burada R0  oda sıcaklığındaki orijinal direnç, R bir sıcaklık değişikliğinden sonra direnç ve ɑ malzemenin sıcaklık katsayısıdır.<img height="20" src="file:///C:/Users/TIMOTH~1/AppData/Local/Temp/msohtmlclip1/01/clip_image006.gif" width="10" />

Direnç

Bir akım herhangi bir iletkenden geçtiğinde, iletken akımın akması için bir miktar zorluğa neden olur. Bu zorluğun ölçüsü biliniyor ...

Education

JoVE Core

Physics

Fizik

Unit 1

Ünite 1

Current and Resistance

Akım ve Direnç

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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

Current Flow in Simple Circuits

Electrical current is the flow of charge in a circuit. A large current means a large amount of charge moves through a wire in a short time. A small current means only a small amount of charge moves through the circuit over a longer time. Examples include the current needed to run a refrigerator and the smaller current used by a handheld calculator. The SI unit for current is the ampere, or amp. It is named for the French physicist André-Marie Ampère (1775–1836). One ampere means one coulomb of...

drift velocity

Electrical Current and Electron Drift

Electrical current in a conductor depends on moving charges and the tiny drift speed of those charges. When a free charge enters a wire, it pushes nearby charges ahead because like charges repel each other. That push spreads through the material very quickly, so the electrical signal moves through the system at nearly the speed of light. This fast signal is not the same as the slow motion of each charge. It is a rapidly spreading change in the electric field, often described as an electrical...

current density

Current Density in Wires and Solutions

Current density describes how much electric current passes through a given cross-sectional area. It helps show not just the size of the current, but also how it is distributed through a conductor. The current density can change from point to point because the local charge flow can vary. If the current flow is uniform, the amount of current is the same at every point along the conductor, even when the conductor’s area changes. Current density is measured in amperes per square meter. Its...

resistivity

Resistivity in Conductors and Insulators

Resistivity describes how much a material opposes electric current. When a voltage is applied to a conductor, an electric field forms. The charges in the conductor feel that force, and a current density develops. In some materials, including metals at a given temperature, the current density is approximately proportional to the electric field. In those cases, current density can be modeled with conductivity, written as sigma. Electrical conductivity is measured in (ohm·m)^−1. It tells how well...

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

Measuring Current, Voltage, and Resistance

Ohm's law describes the relationship between current, voltage, and resistance in many materials. In these cases, the current through a substance is directly proportional to the voltage applied to it. The idea was first shown experimentally by German physicist Georg Simon Ohm, who studied current in a metal wire. A material, component, or device that follows this pattern is called ohmic. An ohmic component has a current that increases in step with voltage. A material or component that does not...

non-ohmic devices

Diode Current and Reverse Bias

A diode is a nonohmic circuit element that makes current and voltage behave differently from Ohm’s law. In most substances, current is proportional to the voltage applied, but a diode does not show a linear current-voltage relationship. A diode is a semiconducting device with two terminals: an anode, which is the positive terminal, and a cathode, which is the negative terminal. It allows current to flow in only one direction. In a simple circuit with a battery, a diode, and a resistor, the...

electrical power

Power Limits in Electrical Circuits

Electrical power in a circuit depends on current and voltage. It is the product of these two values and is measured in watts, or joules per second. That relationship helps explain how much energy a circuit can deliver. A car’s auxiliary power outlet is one real-world example. Some outlets are rated at 20 amps and 12 volts, so they can deliver a maximum of 240 watts. That rating shows the upper limit of power the circuit can provide to devices such as a cell phone charger. Bulb wattage also...

electrical energy

Cutting Electric Bills with Efficient Lighting

Electrical energy is the energy transferred when electrons move from one point to another. The longer an appliance is used, the more electrical energy it consumes. If power stays constant, electrical energy equals the power used by the device times the time it runs. That is why longer use leads to a higher electric bill. Electric bills measure this energy in kilowatt-hours. One kilowatt-hour is equal to 3.6 × 10^6 joules. You can lower electrical energy use by cutting the time an appliance...

continuity equation

Charge Conservation and Current Flow

Charge conservation and current flow are linked through the continuity equation. The current density is the amount of current flowing per unit cross-sectional area. The current through a surface can be written as a surface integral of the current density. The conservation of charge says that the total current leaving a volume equals the rate at which charge inside that volume decreases. The total charge can be written using volume charge density, which is a space function. Because of this, the...

boundary conditions for current density

Current Density at Conductivity Boundaries

Current density at a boundary changes when two conducting materials have different electrical conductivities. The normal component of current density stays continuous across the interface. The tangential component, which runs along the surface, becomes discontinuous across the boundary. Consider two conducting media with conductivities σ1 and σ2 separated by an interface. At point P1 in medium 1, the steady current density makes an angle α1 with the normal. At point P2 in medium 2, the current...

electrical conductivity

Resistance and Ohm's Law in Conductors

Resistance and Ohm's law help explain how electric current moves through a conductor. In a perfect conductor, the electric field inside is zero because free electrons move to cancel it. Any extra charge then stays on the surface. In a practical conductor, an applied electric field can remain in place. That field drives electrons through the material and creates a current. The current density, which is current per unit area, is related to the electric field. More generally, it is related to the...

theory of metallic conduction

Electron Drift in Metallic Conduction

Electron drift in metallic conduction explains how free electrons move through a conductor. A classical model can describe this motion closely, even though quantum mechanics gives the best overall picture. This model is called the theory of metallic conduction. In this theory, Newton's second law is used to find the acceleration of an electron when an electric field is applied. The electron's velocity is then found from that acceleration. The electron travels through a crystal of positive ions...

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

physics

JoVE Temel Fizik, kinematik, dinamik, akışkanlar mekaniği, statik, dalgalar ve akustik dahil olmak üzere temel fizik konularının teorisini ve uygulamasını kısa ve anlaşılması kolay animasyonlu videolarla tanıtıyor. Ek olarak, sektör içindeki bilim insanı videoları, dünya çapındaki günümüz laboratuvarlarında gerçekleştirilen klasik ve orijinal araştırma deneylerinde ilgili kavramların uygulanmasını göstermektedir.

PS.PSc.6.3

PS.Phy.4.3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Energy And Waves

Electricity

Electricity And Magnetism

DC circuits

Tennessee Academic Standards

High School

Energy

PHYS.PS3.11

Virginia  Standards of Learning

HIgh School

PS.9

PS.9.b

PS.9.c

PH.8

PH.8.b

Arizona Science Standards

HS+Phy.P4

HS+Phy.P4U1.8

Alabama Course of Study Science

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Waves and Their Applications in Technologies for Information Transfer

9-12.PS.2.3.c

9-12.PS.2.3.d

9-12.P.2.6.b

9-12.P.2.6.d

Florida Department of Education

SC.912.P.10

SC.912.P.10.15

Texas Essential Knowledge and Skills

PHYS.6

PHYS.6.D

PHYS.6.E

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Energy

HS-PS3-6.

Georgia Standards of Excellence

SPS10.

Understanding Electrical Quantities

SP5.

Ohm’s Law

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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.

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Use models to explain magnetism in terms of domains, interactions of poles, and magnetic fields.

PS.PSc.6.4

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

Factors That Affect Electrical Resistance

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