Name: resistivity in conductors and insulators
Uploaded: 2023-04-30T12:38:52.000Z
Duration: 1 min 22 s
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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.6.2

Resistivity

Rezystywność elektryczna jest nieodłączną właściwością materiału, opisującą, jak skutecznie opiera się on przepływowi ładunków.
Rezystywność jest odwrotnością przewodności elektrycznej i można ją zdefiniować w kategoriach pola elektrycznego i gęstości prądu. Jednostką rezystywności w układzie SI jest omomierz.
Dobre przewodniki mają wysoką przewodność, ale niską rezystywność, podczas gdy dobre izolatory mają niską przewodność, ale wysoką rezystywność.
Temperatura wpływa na rezystywność niektórych materiałów. W wielu materiałach zależność jest w przybliżeniu liniowa i można ją modelować za pomocą równania liniowego, gdzie ρ to rezystywność materiału w danej temperaturze, α jest współczynnikiem temperaturowym materiału, a ρ0 to rezystywność w temperaturze pokojowej.
Rezystywność niektórych materiałów, takich jak miedź, wzrasta wraz ze wzrostem temperatury; w innych, takich jak węgiel, rezystywność maleje wraz ze wzrostem temperatury.
W półprzewodnikach współczynnik temperaturowy jest ujemny, co oznacza, że rezystywność maleje wraz ze wzrostem temperatury.

<ol>
	<li>Protokół OpenStax. (2019). Fizyka uniwersytecka Vol. 2. [Wersja internetowa], str. 396 - 398. Źródło: <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>

oporność

Gdy do przewodnika przyłożone jest napięcie, generowane jest pole elektryczne, a ładunki w przewodniku odczuwają siłę wynikającą z pola elektrycznego. Uzyskana gęstość prądu zależy od pola elektrycznego i właściwości materiału. W niektórych materiałach, w tym metalach, w danej temperaturze gęstość prądu jest w przybliżeniu proporcjonalna do pola elektrycznego. W takich przypadkach gęstość prądu można modelować jako:

<img alt="Równanie1" src="/files/ftp_upload/13746/13746_Equation_1.svg" style="text-align: center; height: 16px;" />

gdzie σ to przewodność elektryczna i jest reprezentowana przez (Ω·m)-1. Przewodność elektryczna jest analogiczna do przewodności cieplnej i jest miarą zdolności materiału do przewodzenia lub przesyłania prądu elektrycznego. Przewodniki mają wyższą przewodność elektryczną niż izolatory. Przewodność jest nieodłączną właściwością materiału. Inną nieodłączną właściwością materiału jest jego rezystywność lub oporność elektryczna. Rezystywność materiału jest miarą tego, jak mocno materiał przeciwstawia się przepływowi prądu elektrycznego. Rezystywność można wyrazić jako odwrotność przewodności elektrycznej i jest ona oznaczana grecką literą rho, ρ. Jednostką rezystywności w jednostkach SI jest omomierz. Rezystywność można również zdefiniować jako stosunek pola elektrycznego i gęstości prądu. Im większa rezystywność, tym większe pole potrzebne do wytworzenia danej gęstości prądu. Im niższa rezystywność, tym większa gęstość prądu wytwarzana przez dane pole elektryczne. Jak podano w tabeli 1, dobry& przewodniki wykazują wysoką przewodność i niską rezystywność, podczas gdy dobre izolatory wykazują niską przewodność i wysoką rezystywność.

Tabela 1: Zawiera wartości rezystywności i przewodności dla różnych materiałów.

<table style="margin-left:auto; margin-right:auto; border-collapse: collapse;">
	<tbody>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Materiały</td>
			<td style="color:black; border:1px solid black; text-align:center;">Przewodność, σ 
			(Ω·m)-1</td>
			<td style="color:black; border:1px solid black; text-align:center;">Rezystywność, ρ 
			(Ω·m)</td>
			<td style="color:black; border:1px solid black; text-align:center;">Temperatura 
			Współczynnik, α (°C)-1</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Srebrny</td>
			<td style="color:black; border:1px solid black; text-align:center;">6,29 × 107</td>
			<td style="color:black; border:1px solid black; text-align:center;">1,59 × 10-8</td>
			<td style="color:black; border:1px solid black; text-align:center;">0,0038</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Miedź</td>
			<td style="color:black; border:1px solid black; text-align:center;">5,95 × 107</td>
			<td style="color:black; border:1px solid black; text-align:center;">1,68 × 10-8</td>
			<td style="color:black; border:1px solid black; text-align:center;">0,0039</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Złoty</td>
			<td style="color:black; border:1px solid black; text-align:center;">4,10 × 107</td>
			<td style="color:black; border:1px solid black; text-align:center;">2,44 × 10-8</td>
			<td style="color:black; border:1px solid black; text-align:center;">0,0034</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Aluminium</td>
			<td style="color:black; border:1px solid black; text-align:center;">3,77 × 107</td>
			<td style="color:black; border:1px solid black; text-align:center;">2,65 × 10-8</td>
			<td style="color:black; border:1px solid black; text-align:center;">0,0039</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Wolfram</td>
			<td style="color:black; border:1px solid black; text-align:center;">1,79 × 107</td>
			<td style="color:black; border:1px solid black; text-align:center;">5,60 × 10-8</td>
			<td style="color:black; border:1px solid black; text-align:center;">0,0045</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Węgiel (czysty)</td>
			<td style="color:black; border:1px solid black; text-align:center;">2,86 × 106</td>
			<td style="color:black; border:1px solid black; text-align:center;">3,50 × 10-5</td>
			<td style="color:black; border:1px solid black; text-align:center;">-0,0005</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Krzem</td>
			<td style="color:black; border:1px solid black; text-align:center;"></td>
			<td style="color:black; border:1px solid black; text-align:center;">0,1 – 2300</td>
			<td style="color:black; border:1px solid black; text-align:center;">-0,07</td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Bursztynowy</td>
			<td style="color:black; border:1px solid black; text-align:center;">2,00 × 1015</td>
			<td style="color:black; border:1px solid black; text-align:center;">5 × 1014</td>
			<td style="color:black; border:1px solid black; text-align:center;"></td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Szkło</td>
			<td style="color:black; border:1px solid black; text-align:center;">10-9 – 1014</td>
			<td style="color:black; border:1px solid black; text-align:center;">109 – 1014</td>
			<td style="color:black; border:1px solid black; text-align:center;"></td>
		</tr>
		<tr>
			<td style="color:black; border:1px solid black; text-align:center;">Lucite</td>
			<td style="color:black; border:1px solid black; text-align:center;">6,0 × 10-13</td>
			<td style="color:black; border:1px solid black; text-align:center;">1,3 × 1013</td>
			<td style="color:black; border:1px solid black; text-align:center;"></td>
		</tr>
	</tbody>
</table>

Oporność

Kiedy napięcie jest przykładane do przewodnika, generowane jest pole elektryczne, a ładunki w przewodniku odczuwają siłę spowodowaną polem elektrycznym. Ten...

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Current and Resistance

Natężenie prądu i rezystancja

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Kluczowe terminy i pojęcia

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 a material can conduct electricity. This idea is similar to thermal conductivity, which describes how well a material carries heat. Conductors have higher electrical conductivity than insulators, and conductivity is an intrinsic property of the material.

Resistivity, written as rho, is another intrinsic property. It is the reciprocal of electrical conductivity. In SI units, resistivity is measured in ohm-meter. It can also be defined as the ratio of electric field to current density. A higher resistivity means a larger electric field is needed to produce a given current density. A lower resistivity means the same electric field produces a larger current density.

The transcript also compares common materials. Good conductors have high conductivity and low resistivity. Good insulators have low conductivity and high resistivity. Examples of good conductors include silver, copper, gold, aluminum, and tungsten. Pure carbon has much lower conductivity than these metals. Silicon falls between conductor and insulator values, while amber, glass, and Lucite show very high resistivity and very low conductivity.

Resistivity in Conductors and Insulators

electrical current

Current Flow in Simple Circuits

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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 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

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,...

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Measuring Current, Voltage, and Resistance

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key terms and concepts

Learn how resistivity relates to conductivity, electric fields, and current density. See why conductors and insulators behave differently in common materials.

Resistivity in Conductors and Insulators | JoVE K12

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PS.PSc.4.1

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Magnetic Field of a Solenoid

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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.

Resistivity in Conductors and Insulators

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