Name: resistivity in conductors and insulators
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Resistivity

Der elektrische Widerstand ist eine intrinsische Eigenschaft eines Materials und beschreibt, wie effektiv es dem Ladungsfluss widersteht.
Der spezifische Widerstand ist der Kehrwert der elektrischen Leitfähigkeit und kann in Bezug auf das elektrische Feld und die Stromdichte definiert werden. Die SI-Einheit des spezifischen Widerstands ist das Ohmmeter.
Gute Leiter haben eine hohe Leitfähigkeit, aber einen niedrigen spezifischen Widerstand, während gute Isolatoren eine geringe Leitfähigkeit, aber einen hohen spezifischen Widerstand haben.
Die Temperatur beeinflusst den spezifischen Widerstand einiger Materialien. In vielen Materialien ist die Abhängigkeit annähernd linear und kann mit einer linearen Gleichung modelliert werden, wobei ρ der spezifische Widerstand des Materials bei einer Temperatur, α der Temperaturkoeffizient des Materials und ρ0 der spezifische Widerstand bei Raumtemperatur ist.
Bei einigen Materialien, wie z. B. Kupfer, nimmt der spezifische Widerstand mit steigender Temperatur zu, bei anderen, wie z. B. Kohlenstoff, nimmt der spezifische Widerstand mit steigender Temperatur ab.
In Halbleitern ist der Temperaturkoeffizient negativ, was bedeutet, dass der spezifische Widerstand mit steigender Temperatur abnimmt.

<ol>
	<li>OpenStax. (2019). Universitätsphysik Vol. 2. [Web-Version], Seite 396 - 398. Abgerufen von <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>

widerstandsfähigkeit

Wenn eine Spannung an einen Leiter angelegt wird, entsteht ein elektrisches Feld und die Ladungen im Leiter spüren die Kraft aufgrund des elektrischen Feldes. Die resultierende Stromdichte hängt vom elektrischen Feld und den Eigenschaften des Materials ab. Bei einigen Materialien, einschließlich Metallen bei einer gegebenen Temperatur, ist die Stromdichte ungefähr proportional zum elektrischen Feld. In diesen Fällen kann die Stromdichte modelliert werden als:

<img alt="Equation1" src="/files/ftp_upload/13746/13746_Equation_1.svg" style="text-align: center; height: 16px;">

wo σ die elektrische Leitfähigkeit ist und durch (Ω·m)−1 dargestellt wird. Die elektrische Leitfähigkeit ist analog zur thermischen Leitfähigkeit und ist ein Maß für die Fähigkeit eines Materials, Elektrizität zu leiten oder zu übertragen. Leiter haben eine höhere elektrische Leitfähigkeit als Isolatoren. Die Leitfähigkeit ist eine intrinsische Eigenschaft eines Materials. Eine weitere intrinsische Eigenschaft eines Materials ist seine Widerstandsfähigkeit oder elektrische Widerstandsfähigkeit. Die Widerstandsfähigkeit eines Materials ist ein Maß dafür, wie stark ein Material dem Stromfluss entgegenwirkt. Die Widerstandsfähigkeit kann als das Kehrwert der elektrischen Leitfähigkeit angegeben werden und wird durch den griechischen Buchstaben rho, ρ, dargestellt. Die Einheit der Widerstandsfähigkeit in SI-Einheiten ist das Ohm-Meter. Die Widerstandsfähigkeit kann auch als Verhältnis von elektrischem Feld und Stromdichte definiert werden. Je größer die Widerstandsfähigkeit ist, desto größer ist das Feld, das erforderlich ist, um eine bestimmte Stromdichte zu erzeugen. Je niedriger die Widerstandsfähigkeit ist, desto größer ist die Stromdichte, die durch ein bestimmtes elektrisches Feld erzeugt wird. Wie in Tabelle 1 aufgeführt, zeigen gute Leiter hohe Leitfähigkeit und niedrige Widerstandsfähigkeit, während gute Isolatoren eine niedrige Leitfähigkeit und hohe Widerstandsfähigkeit aufweisen.


Tabelle 1: Listet Widerstandsfähigkeits- und Leitfähigkeitswerte für verschiedene Materialien auf.

<div class="overflow"><table style="margin-left: auto; margin-right: auto;">
	<tbody style="border: 1px solid black;">
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">Materials</td>
			<td style="color: black; border: 1px solid black; text-align: center;">Conductivity, σ 
			( Ω · m)−1</td>
			<td style="color: black; border: 1px solid black; text-align: center;">Resistivity, ρ 
			( Ω · m)</td>
			<td style="color: black; border: 1px solid black; text-align: center;">Temperature 
			Coefficient, α (°C)−1</td>
		</tr>
		<tr>
			<td style="color: black; border: 1px solid black; text-align: center;">Silver</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;">Copper</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;">Gold</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;">Aluminum</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;">Tungsten</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;">Carbon (pure)</td>
			<td style="color: black; border: 1px solid black; text-align: center;">2.86 × 10−6 </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;">Silicon</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;">Amber</td>
			<td style="color: black; border: 1px solid black; text-align: center;">2.00 × 10−15 </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;">Glass</td>
			<td style="color: black; border: 1px solid black; text-align: center;">10−9 − 10−14</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;"><10−13 </td>
			<td style="color: black; border: 1px solid black; text-align: center;">>1013</td>
			<td style="color: black; border: 1px solid black; text-align: center;"></td>
		</tr>
	</tbody>
</table></div>

Widerstandsfähigkeit

Wenn eine Spannung an einen Leiter angelegt wird, wird ein elektrisches Feld erzeugt, und die Ladungen im Leiter spüren die Kraft, die durch das elektrische Feld verursacht wird. Das...

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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.

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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...

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Resistivity in Conductors and Insulators | JoVE K12

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Resistivity in Conductors and Insulators

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