Name: superconductor critical temperature
Uploaded: 2025-05-22T09:05:52.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Physics

PH.9

PH.9.g

Superconductor

Ein Supraleiter ist ein Material, das dem Elektronenfluss keinen Widerstand bietet, mit einer effizienten Übertragung elektrischer Energie und ohne Wärmeverlust.
Heike Kamerlingh Onnes beobachtete 1911, dass der Widerstand gegen Null geht, wenn Quecksilber unter 4,2 Kelvin abgekühlt wird. Dies ist als kritische Temperatur für Quecksilber bekannt, und das Phänomen ist als Supraleitung bekannt.
Wenn die Temperatur über die kritische Temperatur steigt, ändert sich der Widerstand linear mit ihr.
Ein weiterer Aspekt des magnetischen Verhaltens eines Supraleiters wird beobachtet, wenn ein homogenes supraleitendes Material in ein externes, gleichmäßiges Magnetfeld gebracht wird.
Wenn die Temperatur größer als die kritische Temperatur ist, ist das Feld im Inneren des Materials gleich dem externen gleichmäßigen Magnetfeld. Ist sie niedriger als die kritische Temperatur, wird der magnetische Fluss aus dem Material ausgestoßen und das Feld im Inneren ist Null. Dieses Phänomen ist als Meissner-Effekt bekannt.
Die Supraleitung eines Materials unterhalb der kritischen Temperatur kann eliminiert werden, indem die minimale Größe des Magnetfelds angewendet wird, die als kritisches Magnetfeld bezeichnet wird.

<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/9-6-superconductors">https://openstax.org/books/university-physics-volume-2/pages/9-6-superconductors</a></li>
</ol>

superleiter

Ein Stoff, der den Zustand der Supraleitung erreicht, in dem magnetische Felder nicht eindringen können und es keinen elektrischen Widerstand gibt, wird als Superleiter bezeichnet. Im Jahr 1911 bemerkte Heike Kamerlingh Onnes, ein niederländischer Physiker von der Universität Leiden, einen Zusammenhang zwischen der Temperatur und dem Widerstand des Elements Quecksilber. Die Quecksilberprobe wurde dann mit flüssigem Helium abgekühlt, um die lineare Abhängigkeit des Widerstands von der Temperatur zu untersuchen. Es wurde beobachtet, dass der Widerstand abnahm, wenn die Temperatur sank. Kamerlingh Onnes setzte die Abkühlung der Quecksilberprobe fort und als die Temperatur 4,2 K erreichte, fiel der Widerstand abrupt auf null. Dies ist die kritische Temperatur für Quecksilber, bei der die Quecksilberprobe in eine Phase mit absolutem Nullwiderstand übergeht - dieses Phänomen ist als Supraleitung bekannt. Im Fall von Leitern ist der Widerstand nicht gleich null, sondern kleiner als 0,01 Ω. Es gibt verschiedene Methoden, um sehr kleine Widerstände zu messen, wie die Vierpunktmethode, aber ein Ohmmeter ist für die Prüfung des Supraleitungswiderstands nicht geeignet.

Es wurden auch mehrere andere Materialien entdeckt, die in die supraleitende Phase übergehen, wenn die Temperatur nahe dem absoluten Nullpunkt liegt. Im Jahr 1941 wurde festgestellt, dass eine Legierung aus Niob-Nitrid bei 16 Kelvin supraleitend wird; ähnlich wurde im Jahr 1953 festgestellt, dass Vanadium-Silizium bei 17,5 Kelvin supraleitend wird. Die Temperaturen für den Übergang zur Supraleitung stiegen langsam an. Überraschenderweise zeigen viele gute Leiter wie Kupfer, Silber und Gold keine Supraleitung.

Superleiter

Eine Substanz, die die Supraleitung erreicht, einen Zustand, in dem Magnetfelder nicht eindringen können und es keinen elektrischen Widerstand gibt, wird als ...

Education

Lehre

JoVE Core

Physik

Unit 1

Einheit 1

Electromagnetic Induction

Elektromagnetische Induktion

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

superconductor critical temperature

Superconductivity is the state in which a material has no electrical resistance and magnetic fields cannot penetrate it. A material that reaches this state is called a superconductor. The key idea in the transcript is the critical temperature, which is the temperature at which the change happens.

Heike Kamerlingh Onnes of Leiden University first observed this behavior in mercury in 1911. He cooled a mercury sample in liquid helium to study how resistance changed with temperature. As the temperature fell, the resistance also fell. When the temperature approached 4.2 K, the resistance suddenly dropped to zero. That temperature is the critical temperature for mercury, and the mercury sample entered a superconducting phase with absolute zero resistance.

A normal conductor is different because its resistance is not zero, even when it is very small. In the transcript, conductors are described as having resistance less than 0.01 Ω. Very small resistances can be measured with methods such as the four-point method. An ohmmeter, however, is not acceptable for testing superconductivity resistance.

Other materials have also been found in the superconducting phase near absolute zero. In 1941, an alloy of niobium-nitride became superconducting at 16 kelvin. In 1953, vanadium-silicon became superconductive at 17.5 kelvin. These discoveries showed that transition temperatures were slowly increasing. Even so, many good conductors such as copper, silver, and gold do not show superconductivity.

Superconductor Critical Temperature

induction

Magnetic Flux and Induced Current

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Displacement Current in an RC Circuit

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differential form of maxwell's equations

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dc generator

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magnetic damping

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superconductor

Superconductivity is the state in which a material has no electrical resistance and magnetic fields cannot penetrate it. A material that reaches this state is called a superconductor. The key idea in the transcript is the critical temperature, which is the temperature at which the change happens. Heike Kamerlingh Onnes of Leiden University first observed this behavior in mercury in 1911. He cooled a mercury sample in liquid helium to study how resistance changed with temperature. As the...

types of superconductors

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faraday's law

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lenz's law

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motional emf

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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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eddy currents

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displacement current

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significance of displacement current

Maxwell’s Fix for Charging Capacitors

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electromagnetic fields

Electric and Magnetic Fields in Motion

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maxwell's equation of electromagnetism

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symmetry in maxwell's equations

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electric generator: alternator

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back emf

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key terms and concepts

Learn how superconductivity appears at a critical temperature, why mercury became a classic example, and how other materials also show zero resistance.

Superconductor Critical Temperature | JoVE K12

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Superconductor Critical Temperature

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