Name: how thermometers measure heat
Uploaded: 2023-04-30T12:29:09.000Z
Duration: 1 min 22 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry

CHEM.13

CHEM.13.D

Thermometers and Temperature Scales

Ein Thermometer ist ein Gerät, mit dem die Temperatur eines Körpers oder Objekts gemessen wird.
Einige der wichtigsten Arten von Thermometern sind Flüssigkeits-in-Glas-, Bimetall-, Digital-, Infrarot- und Gasthermometer.
Thermometer messen die Temperatur auf drei Hauptskalen: Celsius, Fahrenheit und Kelvin. Diese Skalen wurden auf der Grundlage des Gefrier- und Siedepunkts von Wasser entwickelt.
Auf der Celsius-Temperaturskala wird der Gefrierpunkt von Wasser mit Null angegeben, während der Siedepunkt von Wasser mit hundert angegeben ist. Zwischen diesen beiden Punkten liegen Hundert-Grad-Abstände, weshalb sie auch als Celsius-Skala bekannt ist.
Hier ist die Einheit der Temperatur Grad Celsius.
Auf der Fahrenheit-Temperaturskala wird der Gefrierpunkt von Wasser bei 32 angegeben, während der Siedepunkt bei 212 liegt. Die Einheit der Temperatur auf dieser Skala ist Grad Fahrenheit.
Die Temperatur auf der Fahrenheit-Skala kann leicht in Celsius umgerechnet werden, indem die Umrechnungsgleichung verwendet wird.
Die Kelvin-Temperaturskala ist eine absolute Temperaturskala. Null Kelvin steht hier für den absoluten Nullpunkt, also die niedrigstmögliche Temperatur.

<ol>
	<li>OpenStax. (2019). Universitätsphysik Vol. 2. [Webversion]. Abgerufen von <a href="https://openstax.org/books/university-physics-volume-2/pages/1-2-thermometers-and-temperature-scales">https://openstax.org/books/university-physics-volume-2/pages/1-2-thermometers-and-temperature-scales</a></li>
</ol>

thermometer und temperaturskalen

Jede physikalische Eigenschaft, die konsequent und reproduzierbar von der Temperatur abhängt, kann als Grundlage für ein Thermometer verwendet werden. Zum Beispiel nimmt das Volumen bei den meisten Substanzen mit steigender Temperatur zu. Diese Eigenschaft bildet die Grundlage für das gängige Alkoholthermometer und die ursprünglichen Quecksilberthermometer. Andere Eigenschaften, die zur Messung der Temperatur verwendet werden, sind der elektrische Widerstand, die Farbe und die Abgabe von Infrarotstrahlung.

Da viele physikalische Eigenschaften von der Temperatur abhängen, ist die Vielfalt an Thermometern bemerkenswert. Bei der häufigsten Art von Thermometer, dehnt sich der Alkohol der einen roten Farbstoff enthält schneller aus als das umhüllende Glas. Wenn die Temperatur des Thermometers steigt, wird die Flüssigkeit aus dem Kolben in ein enges Röhrchen gedrückt, was zu einer großen Veränderung der Länge der Säule bei einer geringen Temperaturänderung führt. Eine weitere gängige Art von Thermometer ist das Pyrometer. Ein Pyrometer misst die Infrarotstrahlung (deren Emission mit der Temperatur variiert) von der Quelle und liefert schnell eine Temperaturanzeige. Infrarotthermometer werden auch häufig zur Messung der Körpertemperatur verwendet, indem sie sanft in den Gehörgang eingeführt werden. Solche Thermometer sind genauer als Alkoholthermometer, die unter die Zunge oder unter die Achselhöhle gelegt werden.

Thermometer messen die Temperatur gemäß definierten Messskalen. Die drei häufigsten Temperaturskalen sind Fahrenheit, Celsius und Kelvin. Temperaturskalen werden erstellt, indem zwei reproduzierbare Temperaturen identifiziert werden, häufig die Gefrier- und Siedetemperaturen von Wasser bei Standardatmosphärendruck.

Thermometer und Temperaturskalen

Jede physikalische Eigenschaft, die konsistent und reproduzierbar von der Temperatur abhängt, kann als Grundlage für ein Thermometer verwendet werden. Zum Beispiel nimmt das Volumen zu ...

Education

Lehre

JoVE Core

Physics

Physik

Unit 1

Einheit 1

Temperature and Heat

Temperatur und Wärme

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

how thermometers measure heat

Thermometers measure temperature by using physical properties that change in a predictable way. One common example is volume. For most substances, volume increases as temperature rises. That idea is used in alcohol thermometers and in the original mercury thermometers.

Other thermometer designs use different temperature-sensitive properties. Some measure electrical resistance, color, or the emission of infrared radiation. The alcohol thermometer is a common example. It contains red-dyed alcohol that expands faster than the glass around it. As the liquid warms, it moves from the bulb into a narrow tube. That creates a large change in the length of the liquid column for a small temperature change.

A pyrometer is another type of thermometer. It measures infrared radiation from a source, and its output changes with temperature. It can give a temperature readout very quickly. Infrared thermometers are also used to measure body temperature in the ear canal. They are more accurate than alcohol thermometers used under the tongue or under the armpit.

Thermometers use temperature scales to turn measurements into numbers. The three most common scales are Fahrenheit, Celsius, and Kelvin. These scales are built from two reproducible temperatures. The freezing and boiling points of water at standard atmospheric pressure are the most common reference points.

How Thermometers Measure Heat

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Heat and temperature are key ideas in thermodynamics and in everyday life. People often connect temperature with hot and cold, but science gives it a more precise meaning. Temperature is the quantity measured with a thermometer. It is also linked to the average translational kinetic energy of particles. Heat is different from temperature. Heat is energy that moves from one place or material to another because there is a difference in temperature. That difference in temperature keeps heat...

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thermometers and temperature scales

Thermometers measure temperature by using physical properties that change in a predictable way. One common example is volume. For most substances, volume increases as temperature rises. That idea is used in alcohol thermometers and in the original mercury thermometers. Other thermometer designs use different temperature-sensitive properties. Some measure electrical resistance, color, or the emission of infrared radiation. The alcohol thermometer is a common example. It contains red-dyed...

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Heat transfer happens when there is a temperature difference. It can move fast, like through a cooking pan, or slowly, like through the walls of a picnic ice box. Heat transfer appears in many everyday situations, so it is hard to find a place where it does not occur. There are only three ways heat is transferred: conduction, convection, and radiation. A fireplace shows all three at once. Radiation carries most of the heat into the room. Conduction also moves heat into the room, but much more...

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Convection and radiation are two major ways heat moves. In convection, thermal energy is carried by the large-scale flow of matter. Warm air and water rise because they are less dense, so ocean currents and large-scale atmospheric circulation move heat from the tropics toward the poles and move cold air from the poles toward the tropics. Earth’s rotation changes these moving air currents. It interacts with the flow and helps produce the eastward movement of air in the temperate zones.

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Radiation Heat Transfer and Thermographs

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See how thermometers use expansion, infrared radiation, and other temperature-sensitive properties to measure temperature on Fahrenheit, Celsius, and Kelvin scales.

How Thermometers Measure Heat | JoVE K12

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CHEM.13.A

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CHEM.13.B

CHEM.13.C

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How Thermometers Measure Heat

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