Name: thermal equilibrium and the zeroth law
Uploaded: 2025-05-22T09:05:48.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

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High School

Chemistry

Energy

HS-PS3-4

Zeroth Law of Thermodynamics

The zeroth law of thermodynamics states that if any two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other.
To understand this experimentally, consider three beakers filled with water at three different temperatures.
After connecting beaker A with B and beaker B with C, heat transfer will take place.
After a period of time, the water in beaker A arrives at thermal equilibrium with the water in beaker B, and the water in beaker B arrives at equilibrium with the water in beaker C.
On recording the temperature of the beakers, a uniform temperature is observed in all three beakers, which corresponds to the zeroth law of thermodynamics.
The most significant application of the zeroth law of thermodynamics is the different types of thermometers.
When a thermometer is used to measure the temperature of a body, it attains thermal equilibrium by changing its own temperature.
Thus, the measured temperature of the body is actually the temperature of the thermometer.

nulde wet van de thermodynamica

Experimenteel, als object A in evenwicht is met object B, en object B in evenwicht is met object C, dan is object A in evenwicht met object C. Deze verklaring van transitiviteit wordt de ‘nulwet van de thermodynamica’ genoemd. Een koud metalen blok en een heet metalen blok worden bijvoorbeeld beide bij kamertemperatuur op een metalen plaat geplaatst. Uiteindelijk zullen het koude blok en de plaat in thermisch evenwicht zijn. Bovendien zullen het hete blok en de plaat in thermisch evenwicht zijn. Door de nulde wet kunnen we concluderen dat het koude blok en het hete blok ook in thermisch evenwicht zijn. De Britse natuurkundige Ralph Fowler suggereerde in de jaren dertig het getal ‘nul’. Destijds waren de eerste, tweede en derde wet van de thermodynamica al benoemd en genummerd. De nulde wet was zelden genoemd, maar moest eerst besproken worden vóór de andere, dus gaf Fowler er een kleiner getal aan. Beschouw nu het geval waarin A een thermometer is. De nulde wet vertelt ons dat als A een bepaalde temperatuur meet wanneer deze in evenwicht is met B, en deze vervolgens in contact wordt gebracht met C, deze zal geen energie uitwisselen met C; daarom blijft de temperatuurmeting hetzelfde. Met andere woorden: als twee objecten in thermisch evenwicht zijn, hebben ze dezelfde temperatuur.

Nulde wet van de thermodynamica

Experimentally, if object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is in equilibrium with object C. ...

Education

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Physics

Natuurkunde

Unit 1

Onderdeel 1

Temperature and Heat

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KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

thermal equilibrium and the zeroth law

The zeroth law of thermodynamics explains thermal equilibrium between objects. If object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is also in equilibrium with object C. This transitive relationship is the key idea behind the law.

A simple example uses metal blocks and a metal plate at room temperature. A cold metal block and a hot metal block are both placed on the plate. Over time, the cold block and the plate reach thermal equilibrium, and the hot block and the plate do too. By the zeroth law, the cold block and the hot block are then also in thermal equilibrium.

The law also helps explain how thermometers work. If a thermometer is in equilibrium with one object and then placed in contact with another object, it will not exchange energy with that object if their temperatures match. Its reading stays the same. In other words, two objects in thermal equilibrium have the same temperature.

The name zeroth law was suggested by British physicist Ralph Fowler in the 1930s. By then, the first, second, and third laws of thermodynamics had already been named. The zeroth law was less often stated, but it had to be discussed before the others, so Fowler gave it the smaller number.

Thermal Equilibrium and the Zeroth Law

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zeroth law of thermodynamics

The zeroth law of thermodynamics explains thermal equilibrium between objects. If object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is also in equilibrium with object C. This transitive relationship is the key idea behind the law. A simple example uses metal blocks and a metal plate at room temperature. A cold metal block and a hot metal block are both placed on the plate. Over time, the cold block and the plate reach thermal equilibrium, and...

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key terms and concepts

Learn how the zeroth law of thermodynamics shows that objects in thermal equilibrium have the same temperature and why this matters for thermometers.

Thermal Equilibrium and the Zeroth Law | JoVE K12

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HS-PS3-6

Thermal Equilibrium and the Zeroth Law

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