The definitions of reversible processes given in introductory physics books are found to be vague and misleading. An operational definition suitable for introductory texts is presented that avoids these problems. It stresses that to properly describe reversible processes, the second law of thermodynamics must be used. The constancy of entropy, which defines a reversible process, also distinguishes reversible processes from quasi-static processes.

Topics
Laws of thermodynamics, Ideal gas, Reversible process, Entropy, Friction, Irreversible process, Thermodynamic properties, Educational aids, Books, Abstracts
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8.

The Kelvin–Planck statement of the second law of thermodynamics states that, “No device is possible whose sole effect is to transform a given amount of heat completely into work,” as presented in Ref. 3, p. 520.

9.

The Clausius statement of the second law of thermodynamics states that, “Heat flows naturally from a hot object to a cold object; heat will not flow spontaneously from a cold object to a hot object,” as presented in Ref. 3, p. 517.

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11.

Note that the term adiabatic is used with different meanings in different parts of physics. In the Carnot cycle, adiabatic implies the absence of heat exchange with the environment.

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© 2007 American Association of Physics Teachers.
2007
American Association of Physics Teachers
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