Which law of thermodynamics provides the basis for the concept of temperature?
- A.The zeroth law
- B.The first law
- C.The second law
- D.The third law
Correct answer
Explanation
The correct answer is A, the zeroth law. It states that if body A is in thermal equilibrium with body C, and body B is also in thermal equilibrium with body C, then A and B are in thermal equilibrium with each other. That is precisely what allows a thermometer to be used: the thermometer plays the part of the third body, and two objects that give it the same reading have the same temperature.
Option B, the first law, deals with energy accounting and not with the meaning of temperature. Option C, the second law, fixes the direction in which heat flows and sets a limit on the efficiency of engines. Option D, the third law, concerns behaviour near absolute zero. The zeroth law was recognised and named after the other three had already been numbered, which is why it carries the number zero.
Read the full article: Heat and Thermodynamics: Laws, Latent Heat and Transfer
Practice Questions
View allThe SI unit of heat is the
- A.Calorie
- B.Joule
- C.Kelvin
- D.Watt
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Heat is a form of energy in transit, so it is measured in the same unit as work and energy, the joule, which is one newton metre.
Read the full explanation →Water has its maximum density at a temperature of
- A.0 degrees Celsius
- B.4 degrees Celsius
- C.100 degrees Celsius
- D.Minus 4 degrees Celsius
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Water behaves abnormally between zero and four degrees: it contracts as it is heated in that range and expands again above four degrees, so the same mass occupies its least volume, and therefore has its greatest density, at four degrees Celsius.
Read the full explanation →The latent heat of vaporisation of water is about
- A.80 calories per gram
- B.540 calories per gram
- C.336 calories per gram
- D.2260 calories per gram
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This is the heat that one gram of water at a hundred degrees Celsius must absorb to become steam at the same temperature, with no rise in temperature at all; the same quantity is released when steam condenses back to water.
Read the full explanation →In a vacuum flask, the vacuum between the two walls prevents heat transfer mainly by
- A.Conduction and convection
- B.Radiation only
- C.Conduction only
- D.Neither conduction nor convection
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Both of these modes need matter: conduction passes energy from particle to particle and convection carries it by the movement of a fluid.
Read the full explanation →The first law of thermodynamics is essentially a statement of
- A.The conservation of energy
- B.The increase of entropy
- C.Thermal equilibrium
- D.The unattainability of absolute zero
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The first law says that the heat supplied to a system is equal to the increase in its internal energy plus the external work it does.
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